Friction Calculator
Friction force from the coefficient of friction and the object's weight.
Quick answer
- Formula: F = μ × N; N = m × g on a horizontal surface, g = 9.80665 m/s²
- Worked example — Normal force (= weight): 98.0665 N (full example below).
Friction Calculator
| Normal force (= weight) | 98.0665 N |
| Friction force (max static / kinetic) | 49.0332 N |
A 10 kg box (weight 98.07 N) with μ = 0.5 experiences up to 49.03 N of friction — you must push harder than that to start it sliding.
The friction force between two surfaces is proportional to how hard they are pressed together: F = μ × N, where N is the normal force and μ is the coefficient of friction for the pair of materials.
On a flat horizontal surface the normal force equals the object's weight, mg, with g = 9.80665 m/s². Enter the mass and μ; the normal force is shown so you can check it. For static friction this is the maximum available force — actual static friction adjusts up to this limit to match any applied force.
The formula
Worked example
A 10 kg box (weight 98.07 N) with μ = 0.5 experiences up to 49.03 N of friction — you must push harder than that to start it sliding.
The example is pre-loaded in the result panel — press Calculate with your own numbers to replace it.
Frequently asked questions
Does friction depend on contact area?
In the standard textbook model, no — friction depends only on μ and the normal force. Real surfaces can deviate, but F = μN is the model used in physics and engineering estimates.
What is the difference between static and kinetic μ?
Static μ (for surfaces at rest) is usually higher than kinetic μ (for sliding surfaces), which is why an object takes more force to start moving than to keep moving. Use the μ that matches your situation.
Category: Science calculators
Sources & methodology
This calculator applies the formula shown on this page exactly as written, using the standard definitions for its inputs. Results are computed from the values you enter — no data is stored — and are rounded only for display.
Content last reviewed by CalcHub Editorial.
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