Torque Specs in Nm, lb-ft or kgf·m? A Torque Wrench Walkthrough

To set a torque wrench to a spec written in another unit, convert the number and round to the nearest mark on the wrench. 1 N·m is 0.7376 lb·ft, so a 110 N·m wheel-nut spec becomes about 81 lb·ft. Going the other way, 1 lb·ft is 1.3558 N·m. Older Japanese manuals use kilogram-force meters, where 1 kgf·m is 9.807 N·m.

The math is simple; what goes wrong is reading the wrong unit. Below is a walkthrough for a real job, plus the conversions you'll meet on bikes and engines.

Walkthrough: tightening wheel nuts after a tire change

Say you've swapped to winter wheels and the owner's manual lists the lug nut torque as 110 N·m. Your click-type wrench is American and its main scale is in lb·ft.

1. Convert the spec. 110 N·m is 81.13 lb·ft.
2. Round sensibly. Most wrenches click in 1 lb·ft steps, so set it to 81. Even rounding up to 82 is only about 1% over spec, well inside the tolerance of a typical click wrench.
3. Snug the nuts first by hand or with the wrench on a low setting, in a star pattern, while the car is still on the jack.
4. Lower the car so the tire can't spin, and then torque each nut to 81 lb·ft, again in a star pattern. Stop at the first click. Pulling past it adds torque.
5. Re-check after a short drive. Many tire shops suggest checking again after the first 50 to 100 km, because alloy wheels can settle.

Here are some common wheel-nut values and their equivalents. Always use the figure from your own vehicle's manual.

Manual says	In lb·ft	In kgf·m
80 N·m	59.0	8.16
100 N·m	73.8	10.2
110 N·m	81.1	11.2
120 N·m	88.5	12.2
140 N·m	103.3	14.3

If your manual is in lb·ft and your wrench is metric, run it the other way. 80 lb·ft is 108.5 N·m and 100 lb·ft is 135.6 N·m.

Why are there so many torque units?

Torque is force multiplied by the length of the lever. Every combination of force unit and length unit gives you a torque unit:

• N·m (newton-meter) is the SI unit and appears in most modern manuals worldwide.
• lbf·ft (pound-foot) is the US automotive standard. "Foot-pound" and "ft-lb" mean the same thing when someone is talking about tightening.
• lbf·in (pound-inch) is used for small fasteners, where pound-feet would give awkward decimals. 12 lbf·in make 1 lbf·ft.
• kgf·m and kgf·cm come from older metric and Japanese service literature. 1 kgf·m is 100 kgf·cm.
• N·cm and ozf·in show up on tiny screws, electronics and RC models.

The Torque Converter covers all eight: N·m, kN·m, N·cm, lbf·ft, lbf·in, ozf·in, kgf·m and kgf·cm.

The two mistakes that strip threads

The 12x mistake: lb·in vs lb·ft. Bike components often say something like "5 N·m". That's 44.3 lbf·in, but only 3.7 lbf·ft. If a converted spec of "44" ends up on a wrench scaled in pound-feet, you are applying twelve times the intended torque to a carbon handlebar clamp. The reverse happens too. A spec of 40 lbf·in (3.33 lbf·ft, or 4.52 N·m) misread as 40 lbf·ft would be 54.2 N·m on a small bolt.

The 100x mistake: kgf·cm vs kgf·m. An old motorcycle manual might list 11 kgf·m for an axle nut, which is 107.9 N·m (79.6 lbf·ft). Another bolt might say 110 kgf·cm, which is only 10.8 N·m. The digits look alike but the values are a factor of ten apart, and if the unit is lost when you copy the number down, you can be off by a factor of a hundred.

Both come from carrying a number without its unit. Write the unit next to every converted figure, and recheck anything that looks odd for the bolt size.

How to convert a torque spec in the tool

1. Open the converter and type the spec into Value.
2. In From, choose the unit printed in your manual, for example "Newton-meter (N·m)" or "Kilogram-force meter (kgf·m)".
3. In To, choose the unit on your wrench's scale. The ⇄ button swaps the two if you got them backwards.
4. Read the result. The table below it shows the same torque in every unit, which is handy when a wrench has both a lbf·ft and a N·m scale, or when you need lbf·in for a small driver.

The conversion runs entirely in your browser and shows up to 10 significant digits. That's far more precision than any hand tool has, so round to your wrench's marks.

Engine torque on spec sheets

The same conversion applies to engine and motor specs. A diesel pickup advertised at 300 lb·ft makes 406.7 N·m. A European EV quoting 400 N·m makes 295 lb·ft. Torque only tells half the story, though. Peak power depends on torque and rpm together, and you can convert that side of the brochure with the Power Converter.

FAQ

Is torque in foot-pounds the same as energy in foot-pounds?

The units have the same dimensions but they describe different things. Torque is a twisting force and energy is work done over a distance. That's why engineers write lbf·ft for torque and ft·lbf for energy. For energy, use the Energy Converter.

How accurate does my conversion need to be?

Click-type torque wrenches are usually rated to within a few percent, so one decimal place is plenty. Rounding 81.13 lb·ft to 81 makes no practical difference.

My spec is a range, like 100–120 N·m. What do I set?

Convert both ends (73.8–88.5 lb·ft) and aim for the middle of the range unless the manual says otherwise.

Look up your next spec with the free Torque Converter.