The exact factor for inch-pounds to newton-metres
Both are units of torque — a turning force applied at a distance. The factor comes from the exact definitions: 1 pound-force = 4.4482216 N and 1 inch = 0.0254 m, so 1 in-lb = 0.11298483 Nm. Going back the other way, 1 Nm is about 8.85 in-lb.
Common torque values (in-lb ↔ Nm)
| Inch-pounds | Newton-metres | Foot-pounds |
|---|---|---|
| 10 in-lb | 1.13 Nm | 0.83 ft-lb |
| 25 in-lb | 2.82 Nm | 2.08 ft-lb |
| 50 in-lb | 5.65 Nm | 4.17 ft-lb |
| 75 in-lb | 8.47 Nm | 6.25 ft-lb |
| 100 in-lb | 11.30 Nm | 8.33 ft-lb |
| 150 in-lb | 16.95 Nm | 12.5 ft-lb |
| 250 in-lb | 28.25 Nm | 20.8 ft-lb |
Typical car fasteners live in this range: a spark plug is around 168–252 in-lb (19–28.5 Nm), an oil-pan bolt around 84–132 in-lb (9.5–15 Nm). Always defer to the model's service manual.
Watch these when converting torque
- Newton-metre is not a joule. Same dimensions, different quantity — a joule is energy, Nm is torque. Never label torque in joules.
- in-lb, lbf·in and lb-in are identical. Different notations for the same pound-force-inch.
- Don't confuse inch-pounds with foot-pounds. One foot-pound is 12 inch-pounds, so mixing them up is a 12× error.
- Dry vs oiled changes the target. A lubricated thread reaches the same bolt tension at a lower torque, which is why specs state "dry" or "oiled". Convert the number, but follow the stated condition.
Common questions
How many newton-metres is 1 inch-pound?
1 in-lb is 0.112985 Nm. Remember it as roughly a ninth: 1 Nm is about 8.85 in-lb going the other way.
Is a newton-metre of torque the same as a joule?
No. They share the same units, but a joule measures energy and a newton-metre measures torque. Standards bodies keep them separate, so never write a torque figure in joules.
How do I convert inch-pounds to foot-pounds first?
Divide by 12, since 12 inch-pounds make 1 foot-pound. So 240 in-lb is 20 ft-lb, which is about 27.1 Nm.
