Brake Torque Calculator
Calculate disc brake stopping torque from pad friction, clamping force, and effective rotor radius.
How it works
- 1Enter the friction coefficient μ of the brake pad material (typically 0.35–0.45 for organic pads).
- 2Input the clamping force each pad applies to the disc and the number of friction faces (2 for a standard floating caliper).
- 3Set the effective disc radius — the distance from the axle centre to the mid-point of the pad — to get braking torque T = μ · F · n · R.
Use cases
- Sizing brake calipers and rotors for custom vehicles or race cars.
- Verifying that a braking system meets a required stopping torque specification.
- Comparing pad materials by evaluating how friction coefficient changes affect braking performance.
Frequently asked questions
What is the effective disc radius?
It is the distance from the wheel axle centre to the centre of the pad contact patch — not the full rotor radius. For a pad spanning 80 mm to 160 mm, the effective radius is (80 + 160) / 2 = 120 mm.
Why use 2 friction faces by default?
A typical caliper presses one pad on each side of the disc, giving 2 friction surfaces. Fixed calipers with 4 or 6 pistons still press 2 pads, so the face count stays 2 per disc.
How does this differ from a clutch torque calculator?
The formula T = μ · F · n · R is identical, but a clutch transmits engine torque during engagement while a brake converts kinetic energy to heat during deceleration, usually at higher temperatures.
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