Torque Converter

Torque is a rotational force — the product of a force applied at a distance from a pivot point. 1 Newton-meter (Nm) is the torque produced by 1 Newton of force applied 1 meter from the pivot. Most automotive torque specifications appear in Nm (European and modern global specs) or foot-pounds (US workshop manuals).

The formula

Torque conversions (all linear, from base unit Nm):

ft-lb  → Nm:  multiply by 1.3558179
Nm     → ft-lb: multiply by 0.7375622  (1 / 1.3558179)

in-lb  → Nm:  multiply by 0.1129848   (1.3558179 / 12)
Nm     → in-lb: multiply by 8.8507457

kgf·m  → Nm:  multiply by 9.80665     (exact; g_n definition)
Nm     → kgf·m: multiply by 0.1019716

Source: NIST SP 811 Table 6.

Practical examples

Example 1 — Wheel lug nuts. Spec is 120 Nm. Convert: 120 × 0.7376 = 88.5 ft-lb.

Example 2 — Spark plug spec in in-lb. Manual says tighten to 156 in-lb. Convert: 156 × 0.1130 = 17.6 Nm.

Example 3 — Japanese manual uses kgf·m. Spec is 5.0 kgf·m. Convert: 5.0 × 9.807 = 49.0 Nm = 36.2 ft-lb.

Common mistakes

• Confusing ft-lb (foot-pounds) with in-lb (inch-pounds). A torque spec in in-lb is 12 times smaller than the same number in ft-lb. 156 in-lb ≠ 156 ft-lb.
• Using a click wrench beyond its calibrated range. Torque wrenches are most accurate between 20% and 80% of their rated capacity. Use an appropriately sized wrench for the fastener spec.
• Not accounting for extension length. An extension on a torque wrench effectively changes the lever arm length. Many torque wrench manufacturers publish a correction formula.

International and regional variations

Quick reference

For tire code decoding, speed ratings, and load index values, see the Tire Size Chart: Speed Ratings & Load Index →.