How to use this calculator
- Enter line pressures. Use front and rear caliper line pressure after proportioning.
- Enter caliper geometry. Set piston diameters and pistons per side for the front and rear calipers.
- Enter friction and radii. Set pad friction, rotor effective radius and tire rolling radius.
- Read bias. Compare front and rear axle brake force and front bias percentage.
How it works
The calculator finds piston area on one side of the caliper, doubles pressure-area force for clamp force, then multiplies by pad friction and effective rotor radius. Axle brake force is two wheel torques divided by tire radius.
Use the brake line pressure calculator first if you are starting from pedal force, then carry bias into the brake heat calculator.
Worked example
Verified against the live calculator
A front axle with 6.9 MPa line pressure, 38.1 mm two-piston calipers per side and 130 mm effective radius can land around a 70% front bias when the rear pressure and rear caliper area are lower.
Frequently asked questions
What is brake bias?
Brake bias is the front/rear split of braking force. This calculator reports the front share based on hydraulic pressure, caliper area, pad friction, rotor radius and tire radius.
Should brake bias always be front-heavy?
Most vehicles need front-biased braking because load transfers to the front axle under deceleration, but the right value depends on tires, weight distribution and setup.
Does this include ABS or proportioning valves?
It accepts different front and rear line pressures, but it does not model ABS, EBD or a nonlinear proportioning valve curve.
Is torque or tire force used for the bias result?
The bias percentage uses tire contact braking force, so tire radius differences are included.
Method & assumptions
- Left and right brake hardware are assumed symmetric on each axle.
- ABS/EBD, tire friction, temperature, pad taper, hose expansion and proportioning valve curves are not modeled.