Torque units explained: lbf·ft, N·m and kgf·m

Last reviewed: 2026-08-29

lbf·ft vs lb-in

Torque is a twisting force applied at a distance, so every torque unit is really a force paired with a length: pound-force times distance, or newton times distance. In the United States, wheel fasteners are specified in pound-feet, written lbf·ft or sometimes just ft-lb. This is the force of one pound applied at the end of a one-foot lever arm.

There is a second, smaller imperial unit that causes real damage when it gets confused with the first: pound-inches, written lbf·in or in-lb. Because a foot is twelve inches, one lbf·ft equals twelve lbf·in. Small fasteners like interior trim clips or some sensor housings are genuinely specified in lbf·in, because their correct torque is small. Wheel lug nuts and bolts are never specified in lbf·in. If a torque wrench or a chart shows a wheel figure that looks unusually small for pound-feet, check the unit before you trust it — reading a lbf·ft number as lbf·in leaves the fastener at a twelfth of the clamp force it needs, and reading a lbf·in wrench setting as though it were lbf·ft would over-torque it twelvefold.

This single factor-of-twelve mix-up is one of the most common and most consequential unit errors a home mechanic can make, precisely because both units share the word 'pound' and the abbreviations look similar at a glance.

N·m

Newton-meters, written N·m, are the metric unit of torque and the one used across most of the world outside the United States. A newton is the metric unit of force, and a newton-meter is that force applied at a one-meter lever arm — the same underlying idea as pound-feet, just built from metric units.

One lbf·ft equals 1.35582 N·m. So a typical passenger car wheel torque of around 100 lbf·ft works out to roughly 135 N·m. Most torque wrenches sold outside North America are scaled in N·m, and many are dual-scale, so knowing this conversion lets you use either wrench confidently on a spec written in the other unit.

N·m is also the unit you will see on most manufacturer service bulletins and factory workshop manuals, even for cars sold in the United States, since those documents are frequently written once for a global engineering audience and only the customer-facing owner's manual is localized to lbf·ft. If you are working from a factory manual rather than a consumer manual, check which unit it is actually using before you dial in a wrench.

kgf·m

Kilogram-force meters, written kgf·m, are an older metric unit that still appears on some torque wrenches and in older service literature, particularly from manufacturers with a long history selling into markets that used this unit before N·m became standard. A kgf·m is the torque produced by a force of one kilogram-force at a one-meter arm.

One kgf·m equals 9.80665 N·m, because a kilogram-force is defined using standard gravity, 9.80665 meters per second squared. Working from lbf·ft, that means one kgf·m is about 7.233 lbf·ft. If you own an older wrench marked only in kgf·m, converting through N·m using this factor gets you to a figure you can cross-check against a modern spec sheet.

You are most likely to run into kgf·m on older Japanese-market service documentation and on some older analogue torque wrenches that predate the wider adoption of N·m as the standard metric torque unit. It is worth recognizing the abbreviation on sight, because it is easy to misread as kg·m (a unit of a completely different physical quantity) if you are skimming quickly.

Converting safely

The safest way to work across units is to pick one unit, convert every figure you are using into it before you touch a fastener, and double-check the conversion rather than trusting a half-remembered rule of thumb. Our free torque converter does the arithmetic for lbf·ft, N·m, kgf·m and lbf·in instantly — see the torque unit converter.

Whatever tool you use, always sanity-check the result against the kind of fastener you are torquing. Wheel lug nuts and bolts on passenger vehicles generally fall somewhere in the range of 70 to 150 lbf·ft, roughly 95 to 200 N·m, or roughly 10 to 21 kgf·m. A converted number wildly outside that range is a signal to stop and re-check which unit you started from, not a signal to keep going.

Keep the wrench itself set correctly too. A dual-scale click wrench usually has a small window or collar that shows which unit is active; it is easy to bump this while adjusting the setting, and a wrench silently switched from N·m to lbf·ft will happily let you over-torque a fastener while reading a number that looks perfectly reasonable.

It also pays to write the unit down alongside the number whenever you note a torque figure for later — on a sticky note in the garage, in a maintenance log, or in your phone. A bare number like '103' is meaningless without its unit attached, and a few weeks later even the person who wrote it down may not remember whether it was lbf·ft, N·m or something else entirely. Get in the habit of writing '103 lbf·ft', never just '103'.

Look up your car: wheel torque specifications by make and model.