Foot-pounds to Newton-meters Converter

The reverse problem comes up with American workshop manuals, aftermarket parts and older vehicles that list torque in foot-pounds, when your wrench or digital torque adapter reads newton-metres. Some common figures:

• 25 ft-lb = 33.8954 Nm
• 35 ft-lb = 47.4536 Nm
• 65 ft-lb = 88.1282 Nm
• 80 ft-lb = 108.47 Nm
• 150 ft-lb = 203.37 Nm

If your display shows one decimal of Nm, 33.8954 becomes a target of 33.9. On a click wrench marked in whole or half Nm, round it to 34.

When the manual gives a range, such as 20–25 ft-lb, convert both ends separately: 27.1164 to 33.8954 Nm. The middle of that range is about 30.5 Nm.

One foot-pound is 1.3558 Nm. Adding a third (multiplying by 4/3) is easy in your head but 1.66% low: 80 ft-lb becomes 106.67 Nm instead of 108.47. Multiplying by 1.36 is only 0.31% high and gives 108.8 Nm, while 1.35 is 0.43% low at 108 Nm. If you use the add-a-third method, add roughly another 2% on top to land near the true value.

Cylinder heads and other critical joints are often tightened in stages, or to a torque followed by a turn through an angle. Convert each torque stage on its own and leave the angle exactly as written, because degrees of rotation have nothing to do with the torque unit.

Write the converted values down before you start, so you are not switching between the phone and the wrench in the middle of the sequence.

The foot-pound is also a unit of work and energy, used for things like impact energy. Numerically the conversion factor is the same, but the energy result belongs in joules, not newton-metres. This page sits in the torque category and labels its answer Nm. For energy problems, write the answer as joules, or use an energy converter, so the two are never confused on paper.