Torque Calculator

If you want to find out how the object rotates when subject to a force, our torque calculator is here to help you.

Torque60 N·m150 N × 0.4 m × sin 90°

In pound-feet44.2537 lbf·ft

Effective lever arm0.4 mthe perpendicular distance from the axis to the line of the force

Wasted force component0 Nnone — the force is perpendicular, which is optimal

Angular acceleration produced120 rad/s²τ = Iα, the rotational form of F = ma

Time to reach 3,000 rpm2.618 sfrom rest

Power at 3,000 rpm18.8496 kW25.2777 hp — power is torque times angular velocity

Force needed at twice the lever arm75 Nfor the same torque — which is the whole point of a long spanner

The formula

τ = rF sin θ; τ = Iα

Only the perpendicular part turns anything

Torque is force times the perpendicular distance from the axis to the line along which the force acts. Pull straight along a spanner and nothing turns, no matter how hard you pull, because the sine of zero is zero. Pull at right angles and every newton counts.

The lever arm is the other half. Doubling the length halves the force needed for the same torque, which is why a breaker bar loosens what a short wrench cannot, and why door handles are fitted as far from the hinge as possible.

Power is torque times angular velocity, which is why an engine's peak torque and peak power occur at different speeds: torque is the twist available, power is the rate of doing work, and the second is the first multiplied by how fast it is turning. A high-torque engine at low revs and a low-torque one spinning fast can deliver identical power.