EngineeringFormulaTorque (T)
Torque is a rotational force - the product of a force and the radius at which it's applied.
T = F × r for a force applied perpendicular to a lever arm of length r. It relates to power and rotational speed by P = T × ω (or the equivalent RPM form), which is the relationship the Horsepower calculator uses to convert between torque, speed, and power. Base SI unit is the newton-meter (N·m); US customary work commonly uses pound-feet (lb·ft).
The practical takeaway from T = F × r is that the same force produces more torque at a longer radius - which is exactly why a longer wrench handle makes a stuck bolt easier to turn, and why gear ratios trade torque for speed (or the reverse) without changing the power being transmitted.
Typical Torques by Context
| Context | N·m | lb·ft |
|---|---|---|
| Hand-tightened by feel | 5–10 | 4–7 |
| Passenger-vehicle lug nut | 100–140 | 74–103 |
| Small gasoline engine (idle-range) | 20–40 | 15–30 |
| Large diesel truck engine (peak) | 1,000–2,000+ | 738–1,475+ |
Used In These Calculators
Frequently Asked Questions
Is torque the same thing as work or energy?
They share the same unit dimensionally (force × distance), which is a common source of confusion, but they're different physical concepts. Work/energy is force applied over a displacement in the direction of motion; torque is force applied at a radius, with no requirement that anything actually moves or that energy is transferred.
Why does a longer wrench make a bolt easier to turn?
Because torque is force times radius (T = F × r), for the same required torque a longer handle needs proportionally less applied force. This is also why torque wrenches are calibrated to a specific handle length - the same wrist force produces a different torque reading on a shorter or longer tool.
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