Friction Calculator: Frictional Force and Coeffi...

What is Friction?

Friction is the force resisting relative motion between two surfaces in contact. It is essential to everyday life — without friction, you could not walk, cars could not brake, and screws would not hold. There are two key types: static friction (preventing motion) and kinetic friction (opposing motion already occurring).

🛑 Friction Calculator

Use our free calculator for instant, accurate results.

Calculate Now →

📐 Formula

f = μ × N

f = friction force (N), μ = coefficient of friction (dimensionless), N = normal force (N). μ_static > μ_kinetic for the same surface pair.

📝 Worked Example

A 20 kg box on a floor, μ_kinetic = 0.3:
N = mg = 20 × 9.8 = 196 N
f = 0.3 × 196 = 58.8 N of friction
You need to push with more than 58.8 N to keep it moving.

📝 How to Use the Calculator

Enter MassInput the mass of the object in kg or lbs.

Select Surface PairChoose material combination for μ (wood on wood, rubber on concrete, etc.).

Adjust AngleFor inclined surfaces, enter the angle for normal force correction.

View ResultsGet friction force and the force required to move the object.

❓ FAQ

Why is static friction larger than kinetic friction?

At rest, microscopic surface irregularities interlock more deeply. Once sliding begins, fewer interlocks engage at any given moment.

What does a friction coefficient of 0 mean?

A frictionless surface — a theoretical ideal. Ice approaches 0.03, but true zero friction does not exist for real surfaces.

What is Friction?