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Coefficient Of Friction Calculator

Work out coefficient of friction instantly with clear inputs, formula shown and shareable results.

About Coefficient Of Friction Calculator

The coefficient of friction is the ratio of friction force to normal force, and being a ratio it is dimensionless. 45 N of resistance under a 150 N load gives 0.30. Its arctangent is the angle of friction, the slope at which the object would just begin to slide under its own weight.

Formulas

Coefficient of friction

mu = F(friction) / F(normal)

Angle of friction

phi = arctan(mu)

Worked example

With the default values below, Coefficient Of Friction Calculator returns Coefficient Of Friction of 0.3000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured friction forceminimum 0 N
45 N
Normal force pressing the surfaces togetherminimum 0 N
150 N

Results

Coefficient Of Friction
0.3000
Angle Of Friction
16.699 deg
Friction Force Per Kilogram Of Load
2.942 N/kg
What This Suggests
Low friction - polished or waxed

Step by step

  1. 1Values used
  2. 2Coefficient of friction
  3. 3Angle of friction
  4. 4Coefficient Of Friction= 0.3000
  5. 5Angle Of Friction= 16.699 deg
  6. 6Friction Force Per Kilogram Of Load= 2.942 N/kg
  7. 7What This Suggests= Low friction - polished or waxed

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Does contact area affect friction?

For dry sliding, hardly at all. A wider contact spreads the same load over more area, so the pressure falls and the product stays roughly constant.

What does an angle of friction mean physically?

Tilt the surface to that angle and sliding starts. For mu = 0.3 that is about 16.7 degrees.

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