How to convert Nm to ft lbs
A newton meter (Nm) is the torque of a one newton force acting one meter from the center of a bolt. A pound-foot (lb-ft, often written ft lbs or ft-lb) is a one pound force acting one foot from the center. The pound and the foot both have exact metric definitions, which makes 1 lb-ft exactly 0.45359237 kg × 9.80665 m/s² × 0.3048 m = 1.3558179483 Nm.
lb-ft = Nm ÷ 1.3558179483
Nm = lb-ft × 1.3558179483
lb-in = lb-ft × 12
kgf-m = Nm ÷ 9.80665A kilogram-force meter (kgf-m, also written kg-m or mkg) uses the weight of 1 kg under standard gravity. Standard gravity is defined as exactly 9.80665 m/s², so 1 kgf-m is exactly 9.80665 Nm, or 7.233 lb-ft. You still find it in older manuals.
Worked examples
- 100 Nm ÷ 1.3558179483 = 73.76 lb-ft, which is 885.1 lb-in or 10.197 kgf-m.
- 80 lb-ft × 1.3558179483 = 108.47 Nm.
- 25 Nm = 18.44 lb-ft = 221.3 lb-in.
For a rough mental check, 1 Nm is about three quarters of a lb-ft, and 1 lb-ft is about 1.36 Nm.
Where you meet torque units
- Service manuals: lug nuts, drain plugs, spark plugs and head bolts all have a torque spec. Many manuals print Nm and lb-ft side by side. Small fasteners are often given in lb-in, because the lb-ft figure would be a small number that is hard to set.
- Torque wrenches: many wrenches carry two scales. If yours has only one, convert the spec here and set the wrench to the nearest mark on its scale.
- Engine torque figures: US brochures quote lb-ft, most others quote Nm. An engine rated at 400 Nm makes 295.0 lb-ft. To turn torque and rpm into power, use the horsepower calculator.
Do not mix up lb-ft and lb-in
An inch pound is one twelfth of a foot pound, so a wrench set in the wrong unit is 12 times off. 20 lb-in is only 1.67 lb-ft, and 20 lb-ft is 240 lb-in. Check which unit the spec uses before you pull on the wrench. This page converts numbers only; the correct torque for a fastener is the one in the manual for your vehicle.
Need the wrench size for a bolt as well? See the Wrench size chart on nailsandnumbers.com.
Questions
How many ft lbs is 100 Nm?
100 Nm is 73.76 lb-ft. Divide newton meters by 1.3558179483 to get foot pounds.
How do I convert ft lbs to Nm?
Multiply by 1.3558179483. 80 lb-ft is 108.47 Nm, and 100 lb-ft is 135.58 Nm.
Is ft lbs the same as lb-ft?
For torque, yes. Engineers prefer lb-ft for torque and ft-lb for work or energy, but torque wrenches and manuals use both for the same thing: 1 lb-ft or 1 ft lb is 1.3558 Nm.
How many inch pounds is 1 Nm?
1 Nm is 8.85 lb-in, so 10 Nm is 88.5 lb-in. Going the other way, 1 lb-in is 0.113 Nm.