🛑 Friction Calculator (f = μN)
Find the friction force from the coefficient of friction and the normal force (f = μN), or solve for either.
Friction force f
30 N
Friction force f = μ·N. On a flat surface N = mg; on an incline N = mg·cosθ. Supply your own μ (static or kinetic). 🔒 Computed in your browser.
How the friction calculator (f = μn) works
Friction force is f = μN, where μ is the coefficient of friction (static or kinetic) and N the normal force. On a flat surface N = mg; on an incline N = mg·cos θ. Enter any two of f, μ and N and the tool solves for the third.
Supply your own μ (materials tables vary and drift, so we don’t bundle one): typical values run 0.1–1. Static friction sets the maximum before sliding; kinetic friction acts while sliding.
Frequently asked questions
How do I calculate friction force?
Multiply the coefficient of friction by the normal force: f = μN. For μ = 0.3 and N = 100 N, f = 30 N. Enter μ and N to compute it.
What is the normal force?
The support force perpendicular to a surface. On level ground it equals the weight, N = mg; on a slope of angle θ it is N = mg·cos θ.
What is the difference between static and kinetic friction?
Static friction resists the start of motion (up to a maximum μₛN); kinetic friction acts once sliding, and is usually a bit smaller (μₖ < μₛ). Enter whichever coefficient applies.
Why isn’t a coefficient table built in?
Coefficients depend heavily on exact materials, finish and conditions, and published tables disagree. Enter the μ for your specific case for an accurate result.
Does friction depend on surface area?
To a good approximation, no — friction depends on the normal force and the coefficient, not the contact area.