Work out belt tension instantly with clear inputs, formula shown and shareable results.
The useful work of a belt comes from the difference between tight and slack side tensions, Te = 33,000 x hp / belt speed. How that difference divides between the two sides is set by the capstan relation T1/T2 = e^(mu x theta), so a larger wrap angle or better grip lets the same power be carried with less total tension on the shafts.
Effective tension
Te = 33000 x hp / belt speed fpm
Tension split
T1 / T2 = e^(mu x theta); T1 = Te x e^(mu θ) / (e^(mu θ) - 1)
Te = 33000 x hp / belt speed fpm. The useful work of a belt comes from the difference between tight and slack side tensions, Te = 33,000 x hp / belt speed.
Total shaft load is T1 + T2. Extra tension adds nothing to transmitted power but loads the bearings directly, and bearing life falls with the cube of load.
This calculator takes 4 inputs: Power transmitted, Belt speed, Wrap angle on small pulley, Coefficient of friction. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.