Torque Calculator
Free torque calculator — τ = F × r × sin(θ) in N·m, lb·ft, lb·in, and kg·cm, with angle efficiency shown.
Everyday Uses
Wrench and bolt work
See what force on what lever reaches a fastener's specified torque — before something strips.
Engine spec translation
Convert between N·m and lb·ft to compare cars across regions.
Physics problems
The angle-dependent formula with efficiency shown — rotational mechanics made visible.
Lever design
Size levers, cranks, and handles by the torque they must deliver.
Frequently Asked Questions
What is torque?
The rotational equivalent of force — how strongly something twists. τ = F × r × sin(θ): force times lever arm length times the sine of the angle between them. Pushing 200 N perpendicular on a 0.3 m wrench produces 60 N·m. Same force, longer wrench, more torque — which is why breaker bars exist.
Why does the angle matter?
Only the force component perpendicular to the lever creates rotation. Pushing at 90° uses 100% of your force; at 45° only sin(45°) ≈ 71%; pushing straight along the lever (0°) produces zero torque no matter how hard you push. The calculator shows this efficiency for your angle.
How do N·m and lb·ft relate?
1 N·m = 0.7376 lb·ft, and 1 lb·ft = 1.3558 N·m. Car specs mix them freely: a "300 lb·ft" American engine produces about 407 N·m. Fastener torque specs also appear in lb·in (1 lb·ft = 12 lb·in) for small screws — mixing up lb·ft and lb·in is a classic way to snap bolts.
Why do torque specs matter for bolts?
Correct torque sets the clamping force: too loose and the joint works free under vibration; too tight and you stretch the bolt past yield or strip threads. Critical fasteners (wheel lug nuts, engine head bolts) always carry a specified torque — use a torque wrench, and this calculator to convert units.