What is the difference between static and kinetic friction?

Static friction acts on an object at rest and must be overcome to start motion. Kinetic (sliding) friction acts on an object already in motion. Static friction coefficients are typically higher than kinetic ones for the same material pair.

What units does the calculator use?

Normal force is entered in Newtons (N) and friction force is displayed in Newtons (N). The coefficient of friction is dimensionless.

What is a typical coefficient of friction?

Common values range from about 0.01 (ice on ice) to 1.0+ (rubber on dry concrete). Steel on steel is around 0.15–0.60 depending on lubrication. Most everyday surfaces fall between 0.2 and 0.8.

Can friction force exceed the normal force?

Yes — if the coefficient of friction is greater than 1.0 (common with rubber compounds), the friction force will exceed the normal force. The formula F = μN always holds.

Does friction depend on surface area?

Under the classical Coulomb friction model used here, friction force does NOT depend on contact area — only on the normal force and the coefficient of friction. This holds well for hard, dry surfaces.

Friction Calculator

Calculate friction force (F = μN) from the coefficient of friction and normal force — with common material presets for quick reference.

Inputs

Friction Type

Material Preset (optional)

Coefficient of Friction (μ)

Dimensionless — typically 0.01 to 1.5

Normal Force (N) — Newtons

For an object on a flat surface: N = mass (kg) × 9.81

Result

Enter values above and click Calculate.

Common Coefficients

Material Pair	Static μ	Kinetic μ
Rubber / dry concrete	0.70	0.60
Wood / wood	0.40	0.30
Steel / steel (dry)	0.58	0.42
Steel / steel (lubricated)	0.15	0.10
Ice / ice	0.10	0.03
Teflon / steel	0.04	0.04

Summary

This friction calculator applies the standard formula F = μN to find friction force from the coefficient of friction (μ) and the normal force (N). It supports both static and kinetic friction coefficients, and includes presets for common material pairs such as rubber on concrete, wood on wood, and steel on steel.

How it works

Enter the coefficient of friction (μ) — either type a value or choose a material preset.
Enter the normal force (N) in Newtons.
Select whether you want static or kinetic friction.
Click "Calculate" (or let the live calculation update automatically).
Read the friction force result in Newtons, with a breakdown of the formula used.

Use cases

Solving high-school and college physics problems involving friction.
Engineering design: estimating braking or holding forces.
Checking whether an object on an inclined plane will slide.
Comparing friction forces across different surface material combinations.
Verifying hand calculations in mechanics coursework.
Determining the minimum force required to move an object on a surface.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu