Torque and Power
Explore torque curves, then choose a gear to climb a hill.
P = Tω · ω = 2πn/60
P[kW] = T[N·m] × n[rpm] / 9549.3
9549.3 rounds 30000/π; calculations use π. The two vertical scales differ, so a crossing of the lines has no special meaning.
This fictional engine peaks in torque at 4000 rpm and in power near 5587 rpm. Rising rpm can keep power increasing after torque starts falling.
Simplified educational model. Curves and vehicle values are fictional, not real machine specifications.
How to play
Move the rpm slider to read torque on the solid line and power on the dashed line. Compare switches between three machines. In Hill mode, choose a gear and throttle to reach 100 m. Auto sweeps the graph from low to high rpm; on the hill it selects the gear with the greatest wheel force at the current speed.
Learn more
Torque measures the turning effect on a shaft; power is work per unit time. Since P = Tω, rising rpm can increase power even as torque begins to fall. At peak power, T + n·dT/dn = 0: for a smooth, single-humped torque curve, power peaks on the falling side. Unit conversions use 1 PS = 735.49875 W and 1 hp ≈ 745.7 W (NIST SP 811).
NIST SP 811