Wheel Backspacing Calculator

Backspacing in inches and mm from wheel width and offset (ET).

Formula

Backspacing = Wheel width (inches)/2 + Offset / ET (mm)/25,4 + 0,5 (in)

Assumptions

Assumption: a 0.5-inch flange allowance is added, matching most wheel-fitment calculators.

How to read it

Backspacing is the measurement favoured by the off-road and muscle-car world: the larger it is, the deeper the wheel tucks toward the suspension. Backspacing and offset (ET) describe the same position in two systems — this calculator bridges them.

Continue with

Next tools

Tires & wheelsWheel Offset CalculatorCalculate backspacing, poke and offset (ET) for your wheels.Calculate →Tires & wheelsWheel Inner Clearance CalculatorHow much closer to (or further from) the suspension a new wheel sits compared with the current one.Calculate →Tires & wheelsInches ↔ mm Converter for Wheels & TiresConvert a rim diameter or wheel width between inches and millimetres.Calculate →