Static Friction Calculator
Work out static friction instantly with clear inputs, formula shown and shareable results.
About Static Friction Calculator
Static friction is not a fixed force but a ceiling: it matches whatever you apply, up to mu(s) times the normal force, and only then lets go. A 30 kg block with mu(s) = 0.45 resists up to 132 N, so a 100 N push moves nothing at all. Past the limit the object accelerates on the smaller kinetic friction.
Formulas
Friction ceiling
F(max) = mu(s) x N, with N = mg on the level
Motion test
slides when applied force > F(max)
Worked example
With the default values below, Static Friction Calculator returns Maximum Static Friction of 132.390. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Mass of the objectminimum 0 kg
- 30 kg
- Coefficient of static frictionminimum 0
- 0.45
- Horizontal force appliedminimum 0 N
- 100 N
Results
- Maximum Static Friction
- 132.390 N
- Will It Move?
- The object stays put
- Applied Force Minus Friction Limit
- -32.390 N
- Normal Force
- 294.200 N
Step by step
- 1Values used
- 2Friction ceiling
- 3Motion test
- 4Maximum Static Friction= 132.390 N
- 5Will It Move?= The object stays put
- 6Applied Force Minus Friction Limit= -32.390 N
- 7Normal Force= 294.200 N
Assumptions and limits
- The result is derived only from the 3 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 3 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
Why is it harder to start something moving than to keep it moving?
Static friction coefficients run above kinetic ones, so the force drops once contact is broken - which is why a pushed object often lurches forward.
Does the surplus force give the acceleration?
Roughly, but use the kinetic coefficient once moving. The surplus over static friction is only the instant of breakaway.