KasperCalc: Coefficient of Friction Lookup (Static and Sliding)

Static and Sliding Friction
with references

Look up the static and sliding coefficient of friction for 117 materials and material pairs. Every value carries a small number that links to its source in the reference list at the bottom of the page. Most tables of friction coefficients give a number and no source. Here the core table is traced through a NASA handbook and Marks’ Handbook to the original experimental papers. Rows that cannot be traced are marked as such.

248 rows: 94 traced to original papers, 34 from standards, codes, textbooks and manufacturers’ data sheets, and 120 from web compilations that do not state their source. Filter the table to hide the last group.

Limits, read first.

These are typical values, not design constants. Friction depends on surface finish, surface films, cleanliness and humidity. It also changes with contact pressure, sliding speed, temperature and how long the surfaces have run. A change of 50 percent or more between two real contacts of the same pair is ordinary.
Test the real parts for anything safety-critical: brakes, clutches, clamped and bolted joints, restraints, ramps and anything that holds a load by friction alone.
Lubricated values are for the lubricant named, mostly from laboratory tests of the 1930s to 1950s with pure fatty acids and plain oils. They do not represent modern formulated oils and greases.
The static and the sliding value of one row are not always from the same test. In the core table they have separate sources, shown against each value.
“Unspecified” means the source gives one number and does not say whether it is static or sliding. Treat it as a rough value for either.
Handbook tables disagree. Where two sources give different numbers for the same pair, the rows are kept separate so that you can see the spread.

Friction Table

Search the Table, Then Use a Value

Filter

Search materials or lubricant

Group

Show rows that have

Condition

Only show values with a traceable source (hide web compilations that do not state theirs)

Coefficients of Friction

Materials	Condition	Static, μ_s i	Sliding, μ_k i	Not stated i	Ref. i
Hard steel on Hard steelTraced to the original paper	Dry	0.78⁵	0.42⁶	–	^1,2
Hard steel on Hard steelTraced to the original paper The NASA table prints lubricant letter k for both 0.029 and 0.105 in this column. One of the two letters is probably a misprint, so treat the lubricant for 0.029 as uncertain.	Lubricated: oleic acid (static), turbine oil plus 1 percent graphite (sliding)	0.11⁵	0.029⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: Atlantic spindle oil (light mineral) (static), Atlantic spindle oil plus 2 percent oleic acid (sliding)	0.23⁵	0.081⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: castor oil (static), grease (zinc oxide base) (sliding)	0.15⁵	0.08⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: lard oil (static), graphite (sliding)	0.11⁵	0.058⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: palmitic acid (static), lard oil (sliding)	0.0075²⁰	0.084⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: stearic acid (static), turbine oil plus 1 percent graphite (sliding)	0.0052²⁰	0.105⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: turbine oil plus 1 percent stearic acid (sliding)	–	0.096⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: turbine oil (medium mineral) (sliding)	–	0.108⁸	–	¹
Hard steel on Hard steelTraced to the original paper	Lubricated: oleic acid (sliding)	–	0.12⁸	–	¹
Mild steel on Mild steelTraced to the original paper	Dry	0.74²¹	0.57⁷	–	^1,2
Mild steel on Mild steelTraced to the original paper	Lubricated: oleic acid (sliding)	–	0.09⁷	–	¹
Mild steel on Mild steelTraced to the original paper	Lubricated: rape oil (sliding)	–	0.19⁷	–	¹
Hard steel on GraphiteTraced to the original paper	Dry	0.21⁵	–	–	^1,2
Hard steel on GraphiteTraced to the original paper	Lubricated: oleic acid (static)	0.09⁵	–	–	¹
Hard steel on Babbitt (ASTM No. 1)Traced to the original paper	Dry	0.7¹⁴	0.33⁹	–	^1,2
Hard steel on Babbitt (ASTM No. 1)Traced to the original paper	Lubricated: Atlantic spindle oil (light mineral)	0.23⁵	0.16⁵	–	¹
Hard steel on Babbitt (ASTM No. 1)Traced to the original paper	Lubricated: castor oil	0.15⁵	0.06⁵	–	¹
Hard steel on Babbitt (ASTM No. 1)Traced to the original paper	Lubricated: lard oil	0.08⁵	0.11⁵	–	¹
Hard steel on Babbitt (ASTM No. 1)Traced to the original paper	Lubricated: Atlantic spindle oil plus 2 percent oleic acid (static)	0.085⁵	–	–	¹
Hard steel on Babbitt (ASTM No. 8)Traced to the original paper	Dry	0.42¹⁴	0.35¹⁴	–	^1,2
Hard steel on Babbitt (ASTM No. 8)Traced to the original paper	Lubricated: Atlantic spindle oil (light mineral)	0.17⁵	0.14⁵	–	¹
Hard steel on Babbitt (ASTM No. 8)Traced to the original paper	Lubricated: castor oil	0.11⁵	0.065⁵	–	¹
Hard steel on Babbitt (ASTM No. 8)Traced to the original paper	Lubricated: lard oil	0.09⁵	0.07⁵	–	¹
Hard steel on Babbitt (ASTM No. 8)Traced to the original paper	Lubricated: Atlantic spindle oil plus 2 percent oleic acid (static), stearic acid (sliding)	0.08⁵	0.08¹⁴	–	¹
Hard steel on Babbitt (ASTM No. 10)Traced to the original paper	Lubricated: Atlantic spindle oil (light mineral)	0.25⁵	0.13⁵	–	¹
Hard steel on Babbitt (ASTM No. 10)Traced to the original paper	Lubricated: castor oil	0.12⁵	0.06⁵	–	¹
Hard steel on Babbitt (ASTM No. 10)Traced to the original paper	Lubricated: lard oil	0.1⁵	0.055⁵	–	¹
Hard steel on Babbitt (ASTM No. 10)Traced to the original paper	Lubricated: Atlantic spindle oil plus 2 percent oleic acid (static)	0.11⁵	–	–	¹
Mild steel on Cadmium silverTraced to the original paper	Lubricated: medium mineral oil (sliding)	–	0.097⁶	–	¹
Mild steel on Phosphor bronzeTraced to the original paper	Dry	–	0.34⁷	–	¹
Mild steel on Phosphor bronzeTraced to the original paper	Lubricated: medium mineral oil (sliding)	–	0.173⁶	–	¹
Mild steel on Copper leadTraced to the original paper	Lubricated: medium mineral oil (sliding)	–	0.145⁶	–	¹
Mild steel on Cast ironTraced to the original paper	Dry	–	0.23⁹	–	¹
Mild steel on Cast ironTraced to the original paper	Lubricated: castor oil (static), medium mineral oil (sliding)	0.183¹⁷	0.133⁶	–	¹
Mild steel on LeadTraced to the original paper	Dry	0.95¹⁴	0.95¹⁴	–	¹
Mild steel on LeadTraced to the original paper	Lubricated: medium mineral oil	0.5⁵	0.3¹⁴	–	¹
Nickel on Mild steelTraced to the original paper	Dry	–	0.64⁷	–	¹
Nickel on Mild steelTraced to the original paper	Lubricated: triolein (sliding)	–	0.178⁷	–	¹
Aluminum on Mild steelTraced to the original paper	Dry	0.61¹¹	0.47⁷	–	¹
Magnesium on Mild steelTraced to the original paper	Dry	–	0.42⁷	–	¹
Magnesium on MagnesiumTraced to the original paper	Dry	0.6⁴	–	–	¹
Magnesium on MagnesiumTraced to the original paper	Lubricated: 1 percent lauric acid in paraffin oil (static)	0.08⁴	–	–	¹
Teflon (PTFE) on Teflon (PTFE)Traced to the original paper	Dry	0.04⁴	–	–	¹
Teflon (PTFE) on Teflon (PTFE)Traced to the original paper	Lubricated: medium mineral oil (sliding)	–	0.04⁴	–	¹
Teflon (PTFE) on SteelTraced to the original paper	Dry	0.04⁴	–	–	¹
Teflon (PTFE) on SteelTraced to the original paper	Lubricated: medium mineral oil (sliding)	–	0.04⁴	–	¹
Tungsten carbide on Tungsten carbideTraced to the original paper	Dry	0.2⁴	–	–	¹
Tungsten carbide on Tungsten carbideTraced to the original paper	Lubricated: oleic acid (static)	0.12⁴	–	–	¹
Tungsten carbide on SteelTraced to the original paper	Dry	0.5⁴	–	–	¹
Tungsten carbide on SteelTraced to the original paper	Lubricated: oleic acid (static)	0.08⁴	–	–	¹
Tungsten carbide on CopperTraced to the original paper	Dry	0.35²²	–	–	¹
Tungsten carbide on IronTraced to the original paper	Dry	0.8²²	–	–	¹
Bonded carbide on CopperTraced to the original paper	Dry	0.35²²	–	–	¹
Bonded carbide on IronTraced to the original paper	Dry	0.8²²	–	–	¹
Cadmium on Mild steelTraced to the original paper	Dry	–	0.46⁷	–	¹
Copper on Mild steelTraced to the original paper	Dry	0.53¹¹	0.36⁷	–	¹
Copper on Mild steelTraced to the original paper	Lubricated: oleic acid (sliding)	–	0.18¹⁹	–	¹
Nickel on NickelTraced to the original paper	Dry	1.1¹⁸	0.53⁷	–	¹
Nickel on NickelTraced to the original paper	Lubricated: octyl alcohol (sliding)	–	0.12⁷	–	¹
Brass on Mild steelTraced to the original paper	Dry	0.51¹¹	0.44⁹	–	¹
Brass on Cast ironTraced to the original paper	Dry	–	0.3⁹	–	¹
Zinc on Cast ironTraced to the original paper	Dry	0.85¹⁸	0.21¹⁰	–	¹
Magnesium on Cast ironTraced to the original paper	Dry	–	0.25¹⁰	–	¹
Copper on Cast ironTraced to the original paper	Dry	1.05¹⁸	0.29¹⁰	–	¹
Tin on Cast ironTraced to the original paper	Dry	–	0.32¹⁰	–	¹
Lead on Cast ironTraced to the original paper	Dry	–	0.43¹⁰	–	¹
Aluminum on AluminumTraced to the original paper	Dry	1.05¹⁸	1.4⁷	–	¹
Glass on GlassTraced to the original paper	Dry	0.94¹¹	0.4⁷	–	¹
Glass on GlassTraced to the original paper	Lubricated: palmitic acid (static), oleic acid (sliding)	0.01¹³	0.09⁷	–	¹
Glass on GlassTraced to the original paper	Lubricated: ricinoleic acid (static), 3-in-1 oil (sliding)	0.005¹³	0.116⁷	–	¹
Carbon on GlassTraced to the original paper	Dry	–	0.18⁷	–	¹
Garnet on Mild steelTraced to the original paper	Dry	–	0.39⁷	–	¹
Glass on NickelTraced to the original paper	Dry	0.78¹¹	0.56⁷	–	¹
Copper on GlassTraced to the original paper	Dry	0.68¹¹	0.53⁷	–	¹
Cast iron on Cast ironTraced to the original paper	Dry	1.1¹⁸	0.15¹²	–	¹
Cast iron on Cast ironTraced to the original paper	Lubricated: lard oil (sliding)	–	0.07¹²	–	¹
Cast iron on Cast ironTraced to the original paper	Lubricated: olive oil (sliding)	–	0.064¹²	–	¹
Bronze on Cast ironTraced to the original paper	Dry	–	0.22¹²	–	¹
Bronze on Cast ironTraced to the original paper Printed as 0.77 in the source. That is higher than the dry value and is probably a misprint for 0.077. Check the original before use.	Lubricated: olive oil (sliding)	–	0.77¹²	–	¹
Oak on Oak (parallel to grain)Traced to the original paper	Dry	0.62¹²	0.48¹²	–	¹
Oak on Oak (parallel to grain)Traced to the original paper	Lubricated: dry soap (sliding)	–	0.164¹²	–	¹
Oak on Oak (parallel to grain)Traced to the original paper	Lubricated: lard (sliding)	–	0.067¹²	–	¹
Oak on Oak (perpendicular to grain)Traced to the original paper	Dry	0.54¹²	0.32¹²	–	¹
Oak on Oak (perpendicular to grain)Traced to the original paper	Lubricated: lard (sliding)	–	0.072¹²	–	¹
Leather on Oak (parallel to grain)Traced to the original paper	Dry	0.61¹²	0.52¹²	–	¹
Cast iron on OakTraced to the original paper	Dry	–	0.49¹²	–	¹
Cast iron on OakTraced to the original paper	Lubricated: olive oil (sliding)	–	0.075¹²	–	¹
Leather on Cast ironTraced to the original paper	Dry	–	0.56¹²	–	¹
Leather on Cast ironTraced to the original paper	Lubricated: water (sliding)	–	0.36¹²	–	¹
Leather on Cast ironTraced to the original paper	Lubricated: olive oil (sliding)	–	0.13¹²	–	¹
Laminated plastic on SteelTraced to the original paper	Dry	–	0.35¹⁵	–	¹
Laminated plastic on SteelTraced to the original paper	Lubricated: medium mineral oil (sliding)	–	0.05¹⁵	–	¹
Fluted rubber bearing on SteelTraced to the original paper	Lubricated: water (sliding)	–	0.05¹⁶	–	¹
Steel bolt and nut (carbon or low alloy)Standard, code or handbook Coefficient of friction in the threads, ±20 percent. “Steel” means carbon and low alloy steel, not corrosion resistant steel.	Graphite in petrolatum or oil	–	–	0.07³	³
Steel bolt and nut (carbon or low alloy)Standard, code or handbook	Molybdenum disulphide grease	–	–	0.11³	³
Steel, cadmium platedStandard, code or handbook	None added	–	–	0.12³	³
Steel, zinc platedStandard, code or handbook	None added	–	–	0.17³	³
Steel bolt and nut (carbon or low alloy)Standard, code or handbook	Machine oil	–	–	0.15³	³
Steel on bronzeStandard, code or handbook	None added	–	–	0.15³	³
Corrosion-resistant steel or nickel-base alloys, or silver-plated partsStandard, code or handbook	None added	–	–	0.14³	³
Titanium on steelStandard, code or handbook	Graphite in petrolatum	–	–	0.08³	³
TitaniumStandard, code or handbook	Molybdenum disulphide grease	–	–	0.1³	³
Fasteners in general (design range)Standard, code or handbook The range the source gives for the coefficient between mating threads and under the head.	Depends on materials and lubricant	–	–	0.04 to 1.10¹	¹
Concrete placed monolithicallyStandard, code or handbook λ = 1.0 normalweight concrete, 0.75 all-lightweight.	Shear friction (design)	–	–	1.4λ²⁵	²⁵
Concrete on hardened concrete, clean and intentionally roughened to about 1/4 in.Standard, code or handbook	Shear friction (design)	–	–	1.0λ²⁵	²⁵
Concrete on hardened concrete, clean and not intentionally roughenedStandard, code or handbook	Shear friction (design)	–	–	0.6λ²⁵	²⁵
Concrete on as-rolled structural steel, clean and free of paint, with studs or welded barsStandard, code or handbook	Shear friction (design)	–	–	0.7λ²⁵	²⁵
Mass concrete on Clean sound rockStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.7²⁶	²⁶
Mass concrete on Clean gravel, gravel-sand mixtures, coarse sandStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.55 to 0.60²⁶	²⁶
Mass concrete on Clean fine to medium sand, silty medium to coarse sand, silty or clayey gravelStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.45 to 0.55²⁶	²⁶
Mass concrete on Clean fine sand, silty or clayey fine to medium sandStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.35 to 0.45²⁶	²⁶
Mass concrete on Fine sandy silt, nonplastic siltStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.3²⁶	²⁶
Mass concrete on Very stiff and hard residual or preconsolidated clayStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.40 to 0.50²⁶	²⁶
Mass concrete on Medium stiff and stiff clay and silty clayStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.30 to 0.35²⁶	²⁶
Steel sheet piling on Clean gravel, gravel-sand mixtures, well-graded rock fill with spallsStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.4²⁶	²⁶
Steel sheet piling on Clean sand, silty sand-gravel mixture, single-size hard rock fillStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.3²⁶	²⁶
Steel sheet piling on Silty sand, gravel or sand mixed with silt or clayStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.25²⁶	²⁶
Steel sheet piling on Fine sandy silt, nonplastic siltStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.2²⁶	²⁶
Formed concrete or concrete sheet piling on Clean gravel, gravel-sand mixtures, well-graded rock fill with spallsStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.40 to 0.50²⁶	²⁶
Steel sheet piling interlock on Steel sheet piling interlockStandard, code or handbook	Ultimate friction factor, tan δ	–	–	0.3²⁶	²⁶
Metal on MetalTextbook table	Dry, approximate range	0.15 to 0.60	–	–	²⁷
Metal on WoodTextbook table	Dry, approximate range	0.20 to 0.60	–	–	²⁷
Metal on StoneTextbook table	Dry, approximate range	0.30 to 0.70	–	–	²⁷
Metal on LeatherTextbook table	Dry, approximate range	0.30 to 0.60	–	–	²⁷
Delrin AF100 (PTFE-filled acetal) on SteelManufacturer data sheet	Dry, test PTM 55007	–	0.19	–	²⁸
Delrin 150 (acetal homopolymer) on SteelManufacturer data sheet	Dry, 40 psi and 50 fpm, ASTM D3702	–	0.2	–	^29,35
Nylatron GS (MoS₂-filled nylon 66) on SteelManufacturer data sheet	Dry, test QTM 55007	–	0.2	–	³⁰
Aluminum on AluminumWeb compilation, source not stated Static and sliding as printed in the compilation. The static range includes the 1.05 of the primary table.	Clean and dry	1.05 to 1.35	0.4	–	³¹
Aluminum on AluminumWeb compilation, source not stated	Greasy	–	–	0.3^31,32	^31,32
Aluminum-bronze on SteelWeb compilation, source not stated	Clean and dry	–	–	0.45³¹	³¹
Bronze on SteelWeb compilation, source not stated	Greasy	–	–	0.16^31,32	^31,32
Sintered bronze on SteelWeb compilation, source not stated	Greasy	–	–	0.13³¹	³¹
Phosphor bronze on SteelWeb compilation, source not stated	Clean and dry	–	–	0.35^31,32	^31,32
Copper-lead alloy on SteelWeb compilation, source not stated	Clean and dry	–	–	0.22^31,32	^31,32
Brass on SteelWeb compilation, source not stated	Greasy	–	–	0.19^31,32	^31,32
Brass on SteelWeb compilation, source not stated	Castor oil	–	–	0.11³¹	³¹
Cadmium on CadmiumWeb compilation, source not stated	Clean and dry	–	–	0.5^31,32	^31,32
Cadmium on CadmiumWeb compilation, source not stated	Greasy	–	–	0.05^31,32	^31,32
Cadmium on ChromiumWeb compilation, source not stated	Clean and dry	–	–	0.40 to 0.41^31,32	^31,32
Cadmium on ChromiumWeb compilation, source not stated	Greasy	–	–	0.34 to 0.35^31,32	^31,32
Chromium on ChromiumWeb compilation, source not stated	Clean and dry	–	–	0.41^31,32	^31,32
Chromium on ChromiumWeb compilation, source not stated	Greasy	–	–	0.34^31,32	^31,32
Copper on CopperWeb compilation, source not stated	Clean and dry	–	–	1.0 to 1.6^31,32	^31,32
Copper on CopperWeb compilation, source not stated	Greasy	–	–	0.08^31,32	^31,32
Copper on SteelWeb compilation, source not stated	Greasy	–	–	0.18³¹	³¹
Iron on IronWeb compilation, source not stated	Clean and dry	–	–	1^31,32	^31,32
Iron on IronWeb compilation, source not stated	Greasy	–	–	0.15 to 0.20^31,32	^31,32
Cast iron on SteelWeb compilation, source not stated	Clean and dry	–	–	0.4^31,32	^31,32
Cast iron on SteelWeb compilation, source not stated	Greasy	–	–	0.21^31,32	^31,32
Magnesium on SteelWeb compilation, source not stated	Clean and dry	–	–	0.42³¹	³¹
Nickel on NickelWeb compilation, source not stated	Greasy	0.28	0.12	–	^31,32
Platinum on PlatinumWeb compilation, source not stated	Clean and dry	–	–	1.2^31,32	^31,32
Platinum on PlatinumWeb compilation, source not stated	Greasy	–	–	0.25^31,32	^31,32
Silver on SilverWeb compilation, source not stated	Clean and dry	–	–	1.4^31,32	^31,32
Silver on SilverWeb compilation, source not stated	Greasy	–	–	0.52 to 0.55^31,32	^31,32
Zinc on ZincWeb compilation, source not stated	Clean and dry	–	–	0.6^31,32	^31,32
Zinc on ZincWeb compilation, source not stated	Greasy	–	–	0.04^31,32	^31,32
Cobalt on CobaltWeb compilation, source not stated	Clean and dry, 70 °C	–	–	0.3³²	³²
Steel on SteelWeb compilation, source not stated	Clean and dry	0.50 to 0.80	0.42	–	³¹
Steel on SteelWeb compilation, source not stated	Greasy	–	–	0.16^31,32	^31,32
Steel on SteelWeb compilation, source not stated	Castor oil	0.15	0.081	–	³¹
Steel on SteelWeb compilation, source not stated	Stearic acid	–	–	0.15³¹	³¹
Steel on SteelWeb compilation, source not stated	Light mineral oil	–	–	0.23³¹	³¹
Steel on SteelWeb compilation, source not stated	Lard	0.11	0.084	–	³¹
Steel on SteelWeb compilation, source not stated	Graphite	–	–	0.058³¹	³¹
Steel on GraphiteWeb compilation, source not stated	Clean and dry	–	–	0.21³¹	³¹
Graphite on SteelWeb compilation, source not stated	Clean and dry or greasy	–	–	0.1^31,32	^31,32
Carbon on SteelWeb compilation, source not stated	Clean and dry	–	–	0.14^31,32	^31,32
Carbon on SteelWeb compilation, source not stated	Greasy	–	–	0.11 to 0.14^31,32	^31,32
Carbon (hard) on Carbon (hard)Web compilation, source not stated	Clean and dry	–	–	0.15 to 0.16^31,32	^31,32
Carbon (hard) on Carbon (hard)Web compilation, source not stated	Greasy	–	–	0.12 to 0.14^31,32	^31,32
Graphite on GraphiteWeb compilation, source not stated	Clean and dry	–	–	0.1^31,32	^31,32
Graphite on GraphiteWeb compilation, source not stated	In vacuum	–	–	0.5 to 0.8³¹	³¹
Diamond on DiamondWeb compilation, source not stated	Clean and dry	–	–	0.1^31,32	^31,32
Diamond on DiamondWeb compilation, source not stated	Greasy	–	–	0.05 to 0.10^31,32	^31,32
Diamond on MetalsWeb compilation, source not stated	Clean and dry	–	–	0.10 to 0.15^31,32	^31,32
Sapphire on SapphireWeb compilation, source not stated	Clean and dry or greasy	–	–	0.2³¹	³¹
Mica on MicaWeb compilation, source not stated	Freshly cleaved	–	–	1³¹	³¹
Glass on MetalWeb compilation, source not stated	Clean and dry	–	–	0.5 to 0.7^31,32	^31,32
Glass on MetalWeb compilation, source not stated	Greasy	–	–	0.2 to 0.3^31,32	^31,32
Tungsten carbide on SteelWeb compilation, source not stated	Clean and dry	–	–	0.40 to 0.60^31,32	^31,32
Tungsten carbide on SteelWeb compilation, source not stated	Greasy	–	–	0.10 to 0.20^31,32	^31,32
PTFE on SteelWeb compilation, source not stated	Clean and dry	–	–	0.05 to 0.20³¹	³¹
Nylon on NylonWeb compilation, source not stated	Clean and dry	–	–	0.15 to 0.25^31,32	^31,32
Nylon on SteelWeb compilation, source not stated	Clean and dry	–	–	0.4³¹	³¹
Polyethylene on PolyethyleneWeb compilation, source not stated	Clean and dry	–	–	0.2³¹	³¹
Polyethylene on SteelWeb compilation, source not stated	Clean and dry or greasy	–	–	0.2^31,32	^31,32
Polystyrene on PolystyreneWeb compilation, source not stated	Clean and dry or greasy	–	–	0.5^31,32	^31,32
Polystyrene on SteelWeb compilation, source not stated	Clean and dry or greasy	–	–	0.30 to 0.35^31,32	^31,32
Plexiglas on PlexiglasWeb compilation, source not stated	Clean and dry or greasy	–	–	0.8^31,32	^31,32
Plexiglas on SteelWeb compilation, source not stated	Clean and dry or greasy	–	–	0.40 to 0.50^31,32	^31,32
Wood on WoodWeb compilation, source not stated	Clean and dry	–	–	0.25 to 0.50^31,32	^31,32
Wood on WoodWeb compilation, source not stated	Wet	–	–	0.2^31,32	^31,32
Wood on MetalWeb compilation, source not stated	Clean and dry	–	–	0.20 to 0.60^31,32	^31,32
Wood on StoneWeb compilation, source not stated	Clean and dry	–	–	0.20 to 0.40³¹	³¹
Wood on ConcreteWeb compilation, source not stated	Clean and dry	–	–	0.62^31,32	^31,32
Brick on WoodWeb compilation, source not stated	Clean and dry	–	–	0.6^31,32	^31,32
Masonry on BrickWeb compilation, source not stated	Clean and dry	–	–	0.60 to 0.70^31,32	^31,32
Leather on MetalWeb compilation, source not stated	Clean and dry	–	–	0.4 to 0.6^31,32	^31,32
Leather on MetalWeb compilation, source not stated	Greasy	–	–	0.2^31,32	^31,32
Leather on WoodWeb compilation, source not stated	Clean and dry	–	–	0.30 to 0.40^31,32	^31,32
Leather fibre on Cast ironWeb compilation, source not stated	Clean and dry	–	–	0.31³¹	³¹
Leather fibre on AluminumWeb compilation, source not stated	Clean and dry	–	–	0.3³¹	³¹
Paper on Cast ironWeb compilation, source not stated	Clean and dry	–	–	0.19 to 0.20^31,32	^31,32
Hemp rope on TimberWeb compilation, source not stated	Clean and dry	–	–	0.5³¹	³¹
Cotton on CottonWeb compilation, source not stated	Threads	–	–	0.3³¹	³¹
Silk on SilkWeb compilation, source not stated	Clean	–	–	0.25³¹	³¹
Straw fibre on Cast ironWeb compilation, source not stated	Clean and dry	–	–	0.26³¹	³¹
Straw fibre on AluminumWeb compilation, source not stated	Clean and dry	–	–	0.27³¹	³¹
Tarred fibre on Cast ironWeb compilation, source not stated	Clean and dry	–	–	0.15³¹	³¹
Tarred fibre on AluminumWeb compilation, source not stated	Clean and dry	–	–	0.18³¹	³¹
Rubber on RubberWeb compilation, source not stated	Clean and dry	–	–	1.15 to 1.16^31,32	^31,32
Rubber on Dry asphaltWeb compilation, source not stated	Clean and dry	0.9	0.5 to 0.8	–	^31,32
Rubber on Wet asphaltWeb compilation, source not stated	Wet	–	–	0.25 to 0.75³¹	³¹
Rubber on Dry concreteWeb compilation, source not stated	Clean and dry	–	–	0.60 to 0.85^31,32	^31,32
Rubber on Wet concreteWeb compilation, source not stated	Wet	–	–	0.30 to 0.75^31,32	^31,32
Rubber on CardboardWeb compilation, source not stated	Clean and dry	–	–	0.5 to 0.8³¹	³¹
Car tyre on AsphaltWeb compilation, source not stated	Clean and dry	–	–	0.71 to 0.72^31,32	^31,32
Car tyre on GrassWeb compilation, source not stated	Clean and dry	–	–	0.35 to 0.36^31,32	^31,32
Tyre, dry on Road, dryWeb compilation, source not stated	Clean and dry	–	–	1³¹	³¹
Tyre, wet on Road, wetWeb compilation, source not stated	Wet	–	–	0.2³¹	³¹
Horseshoe on RubberWeb compilation, source not stated The two compilations differ by more than a factor of two for this pair.	Clean and dry	–	–	0.28 to 0.68^31,32	^31,32
Horseshoe on ConcreteWeb compilation, source not stated	Clean and dry	–	–	0.58 to 0.67^31,32	^31,32
Rubber (60 A belt) on Stainless steel 316Web compilation, source not stated	Clean and dry	0.64	–	–	³²
Rubber (60 A belt) on Tool steelWeb compilation, source not stated	Clean and dry	0.86	–	–	³²
Rubber (60 A belt) on Tungsten carbideWeb compilation, source not stated	Clean and dry	0.62	–	–	³²
Rubber (60 A belt) on UHMW polyethyleneWeb compilation, source not stated	Clean and dry	0.56	–	–	³²
Rubber (60 A belt) on Rubber (60 A belt)Web compilation, source not stated	Clean and dry	0.73	–	–	³²
Ice on IceWeb compilation, source not stated	Clean, 0 °C	0.1	0.02	–	³¹
Ice on IceWeb compilation, source not stated	Clean, −12 °C	0.3	0.035	–	³¹
Ice on IceWeb compilation, source not stated	Clean, −80 °C	0.5	0.09	–	³¹
Ice on SteelWeb compilation, source not stated	Clean and dry	–	–	0.03 to 0.04^31,32	^31,32
Ice on WoodWeb compilation, source not stated	Clean and dry	–	–	0.05^31,32	^31,32
Brass on IceWeb compilation, source not stated	Clean, 0 °C	–	–	0.02³¹	³¹
Brass on IceWeb compilation, source not stated	Clean, −80 °C	–	–	0.15³¹	³¹
Aluminum on SnowWeb compilation, source not stated	Wet, 0 °C	–	–	0.4³¹	³¹
Aluminum on SnowWeb compilation, source not stated	Dry, 0 °C	–	–	0.35³¹	³¹
Nylon on SnowWeb compilation, source not stated	Wet, 0 °C	–	–	0.4³¹	³¹
Nylon on SnowWeb compilation, source not stated	Dry, −10 °C	–	–	0.3³¹	³¹
PTFE on SnowWeb compilation, source not stated	Wet, 0 °C	–	–	0.05³¹	³¹
PTFE on SnowWeb compilation, source not stated	Dry, 0 °C	–	–	0.02³¹	³¹
Ski wax on SnowWeb compilation, source not stated	Wet, 0 °C	–	–	0.1³¹	³¹
Ski wax on SnowWeb compilation, source not stated	Dry, 0 °C	–	–	0.04³¹	³¹
Ski wax on SnowWeb compilation, source not stated	Dry, −10 °C	–	–	0.2³¹	³¹
Brake material (composite) on Cast ironWeb compilation, source not stated The compilation warns that a brake value is an average over varying speeds, pressures and temperatures. Static values at ambient temperature can be 40 to 50 percent of it.	Clean and dry	–	–	0.4^31,32	^31,32
Brake material (composite) on Cast ironWeb compilation, source not stated	Wet	–	–	0.2^31,32	^31,32
Human skin on MetalsWeb compilation, source not stated	Clean and dry	–	–	0.8 to 1.0^31,32	^31,32

Small numbers are reference numbers. They link to the list at the bottom of the page. Click a value to use it below. A dash means the source gives no value. Static is the force to start sliding. Sliding is the force to keep it moving.

Quick Use

Coefficient of friction, μ

Type a value, or click one in the table. A range such as 0.4 to 0.6 can be typed as 0.4-0.6.

Normal force pressing the surfaces together

Friction force F = μ N. The angle of friction φ = arctan μ is the slope at which a block just starts to slide under its own weight. A coefficient is dimensionless, so the same number works in any unit system.

From Friction to Bolt Torque

In a threaded fastener, friction in the threads and under the head takes most of the tightening torque. So the torque needed for a given preload depends strongly on friction. The usual shortcut is the torque coefficient K, also called the nut factor, in T = K F d. T is the torque, F is the preload and d is the nominal diameter.

Friction between threads, μ	Friction under head or nut, μ_c	Torque coefficient, K	Ref.
0.05	0.05	0.074	¹
0.10	0.10	0.133	¹
0.15	0.15	0.189	¹
0.20	0.20	0.250	¹

Table VI of the NASA handbook, calculated for equal friction in the threads and under the head, from K = (d_m/2d)[(tanψ + μ secα)/(1 − μ tanψ secα)] + 0.625μ_c. The handbook notes that K = 0.2 is the commonly assumed value but should not be used blindly. It says 0.15 is more typical for steel on steel.

Bolt condition	K	Ref.
Non-plated, black finish	0.30	²³
Zinc plated	0.20	²³
Lubricated	0.18	²³
Cadmium plated	0.16	²³
With anti-seize compound	0.12	²⁴

These torque factors are as reproduced in secondary sources (see references 23 and 24) and are typically quoted with a scatter of ±25 percent. For a joint that matters, measure the torque-tension relationship on the real fasteners. The MIL-HDBK-60 coefficients in the main table are for the threads and the nut face.

What a Coefficient of Friction Is, and Is Not

\[ F \le \mu_s N \quad(\text{at rest}),\qquad F = \mu_k N \quad(\text{sliding}),\qquad \varphi = \arctan\mu \]

The classical laws are credited to Amontons and Coulomb. They say friction force is proportional to the normal force and independent of the apparent area. For sliding, it is also nearly independent of speed. They hold well enough for hard dry metals to be useful. They fail badly for polymers, rubbers, soft metals, ice and lubricated surfaces. There, friction changes with load, area, speed and temperature.

Why static is usually, but not always, higher

Surfaces left in contact bond slightly and shed their films, so the force to start motion is typically higher than the force to keep it moving. The difference is large for clean metals and small for PTFE, which is why PTFE and filled acetals run without slip-stick. The table shows a few pairs (aluminium on aluminium, for example) where the printed sliding value is higher than the static one. These come from different experiments and show how much depends on the test.

What moves the number

Films and contamination. Oxide, adsorbed gas, oil and moisture dominate in air. Clean metals in vacuum can weld, with coefficients above 1.
Surface finish. Very smooth and very rough surfaces can both be higher than a moderate finish.
Pressure, speed and temperature. Polymers and rubber especially.
Run-in and history. A new pair often differs from one that has worn in. The transfer film on a polymer takes time to form.
Lubrication regime. Boundary, mixed and fluid film give very different values, and a coefficient from one regime is not valid in another.

How friction is measured

Four methods are common. They are the inclined plane, the sled on a flat (ASTM D1894 for plastic film, ISO 8295), the pin or ball on disk (ASTM G99) and the thrust washer (ASTM D3702). ASTM G115 is the guide to measuring and reporting friction coefficients. A value without its test method, counterface finish and conditions is only a rough guide.

References & Important Notices

References

Barrett, R. T., Fastener Design Manual, NASA Reference Publication 1228, NASA Lewis Research Center, March 1990. Table IV, “Coefficients of static and sliding friction” (p. 16); Tables V and VI and the torque discussion (pp. 17–18). A US Government work. NASA Technical Reports Server, record 19900009424. Link.
Baumeister, T., Avallone, E. A., and Baumeister III, T. (eds.), Marks’ Standard Handbook for Mechanical Engineers, 8th ed., McGraw-Hill, 1978. The source from which Table IV of reference [1] was reprinted, which gives the original paper for each value. Those papers are listed below from reference 4 on.
MIL-HDBK-60, Threaded Fasteners — Tightening to Proper Tension, U.S. Department of Defense, 12 March 1990. Table II, “Examples of coefficients of friction”, paragraph 110.2. Values are stated to ±20 percent. Link.
Bowden, F. P., and Tabor, D., The Friction and Lubrication of Solids, Oxford University Press (Part I 1950, Part II 1964). Cited in reference 1 for several of the values as its source 22.
Campbell, W. E., Trans. ASME, 1939.
Clarke, G. L., Lincoln, B., and Sterrett, K. F., Proc. API, 1935.
Beare, W. G., and Bowden, F. P., Phil. Trans. Roy. Soc., 1935.
Boyd, J., and Robertson, B. P., Trans. ASME, 1945.
Sachs, G., Zeitschrift für angewandte Mathematik und Mechanik, 1924.
Honda, K., and Yamada, T., Journal of the Institute of Metals, 1925.
Tomlinson, G. A., Phil. Mag., 1929.
Morin, A. J., Académie Royale des Sciences, 1838.
Claypoole, W. R., Trans. ASME, 1943.
Tabor, D., Journal of Applied Physics, 1945.
Eyssen, G., General Discussion on Lubrication, ASME, 1937.
Brazier, A. J., and Holland-Bowyer, General Discussion on Lubrication, ASME, 1937.
Stanton, T. E., Friction, Longmans.
Ernst, H., and Merchant, M. E., Conference on Friction and Surface Finish, M.I.T., 1940.
Gongwer, C. A., Conference on Friction and Surface Finish, M.I.T., 1940.
Hardy, W. B., and Bircumshaw, I., Proc. Roy. Soc., 1925.
Hardy, W. B., and Hardy, J. K., Phil. Mag., 1919.
Shooter, K. V., Research, 4, 1951.
Budynas, R. G., and Nisbett, J. K., Shigley’s Mechanical Engineering Design, McGraw-Hill, chapter on screws, fasteners and the design of nonpermanent joints (table of torque factors K). Values taken as reproduced by AmesWeb (“Torque coefficient K factor table”, citing the 8th edition, p. 427). Not checked against the print edition. Link.
Bowman Distribution, Barnes Group, Fastener Facts, Cleveland, 1985, p. 90. Cited by the SolidWorks Simulation help for the anti-seize and Bowman-Grip torque factors. Not seen directly. Link.
ACI Committee 318, Building Code Requirements for Structural Concrete, American Concrete Institute. Shear friction coefficient table (ACI 318-14 Table 22.9.4.2). λ is 1.0 for normalweight concrete and 0.75 for all-lightweight concrete.
U.S. Department of the Navy, Naval Facilities Engineering Command, Foundations and Earth Structures, Design Manual 7.2, 1984, table of friction factors for dissimilar materials. Values taken as reproduced in the GEO5 help of Fine Ltd. Not seen directly. These are ultimate values. Apply your own factor of safety. Link.
Beer, F. P., Johnston, E. R., and Mazurek, D. F., Vector Mechanics for Engineers: Statics, 11th ed., McGraw-Hill, Table 8.1, “Approximate values of coefficient of static friction for dry surfaces”. Values taken from a university lecture transcription of the table.
DuPont (Delrin®), Delrin® AF100 Blend (acetal homopolymer, PTFE-filled) product data sheet, 2013: coefficient of friction, dynamic, dry versus steel, test PTM 55007, 0.19.
DuPont (Delrin®), Delrin® 150 (acetal homopolymer) product data sheet, 2014: dynamic coefficient of friction 0.2 at 40 psi and 50 fpm, test ASTM D3702.
Mitsubishi Chemical Advanced Materials (formerly Quadrant), Nylatron® GS nylon, extruded MoS₂-filled type 66 product data sheet, 2019: dynamic coefficient of friction 0.20 dry versus steel, test QTM 55007.
The Engineering ToolBox, Friction — Coefficients for Common Materials and Surfaces, 2004. A web compilation that does not give a source for individual values. Used here only for materials that the primary references do not cover, and marked as such. Link.
Engineers Edge, Coefficients of Friction. A web compilation described as “various industry standards, publications, organizational documentation”. No source is given for individual values. Marked as such. Link.
ASTM G115, Standard Guide for Measuring and Reporting Friction Coefficients. How friction coefficients are measured and what a report should state.
ASTM D1894, Standard Test Method for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting.
ASTM D3702, Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine.
ASTM G99, Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus.
ISO 8295, Plastics — Film and sheeting — Determination of the coefficients of friction.

Lubricant key for the core table

The lettered lubricants of reference 1, Table IV. Where a row shows one lubricant for the static value and another for the sliding value, they came from different tests.

Letter	Lubricant
a	oleic acid
b	Atlantic spindle oil (light mineral)
c	castor oil
d	lard oil
e	Atlantic spindle oil plus 2 percent oleic acid
f	medium mineral oil
g	medium mineral oil plus 1/2 percent oleic acid
h	stearic acid
i	grease (zinc oxide base)
j	graphite
k	turbine oil plus 1 percent graphite
l	turbine oil plus 1 percent stearic acid
m	turbine oil (medium mineral)
n	olive oil
p	palmitic acid
q	ricinoleic acid
r	dry soap
s	lard
t	water
u	rape oil
v	3-in-1 oil
w	octyl alcohol
x	triolein
y	1 percent lauric acid in paraffin oil

Important notices

How the core table was made. The values in the core table were read from Table IV of NASA RP-1228 (reference 1). That table is reprinted from Marks’ Handbook (reference 2). For each value that table gives a number that identifies the original paper. Those numbers are converted here to the references 4 to 22. The original papers were not re-read. The source of each value is as stated by the handbook.
Rows from web compilations. The sites listed in references 31 and 32 give a table of values and no source for each. They are used here only for materials the traced sources do not cover. They are labelled “web compilation, source not stated” and can be hidden with the filter. They are also the origin of some mis-transcribed values elsewhere on the web, which is a reason to prefer traced rows.
Values that look wrong. The lubricated value for bronze on cast iron is printed as 0.77 in the NASA table. That is above the dry value and is probably a misprint for 0.077. It is shown as printed and flagged. A few other published values (the babbitt and cast iron entries, for example) are within the normal scatter but should not be read as precise.
Secondary reproductions. References 23, 24, 26 and 27 were read as reproduced by the site or document named, not in the original printed book or manual. Check them against the print edition before using them in a design.
No endorsement. None of the publishers, standards bodies or manufacturers named has reviewed or approved this page.
Reference aid, not a substitute for testing. Friction is a property of a particular contact, not of two materials. Use the values for first estimates, and measure the real contact for anything that carries a load or is safety-critical.

Coefficient of Friction Lookup

Why static is usually, but not always, higher

What moves the number

How friction is measured

References

Lubricant key for the core table

Important notices

Cite This Work