How do I convert foot-pounds to newton-metres?

Multiply foot-pounds by 1.35582. So 100 ft·lb is 135.6 N·m. Going the other way, divide N·m by that same figure. This tool takes whatever unit you enter and shows all four at once, so you never have to remember which way the multiplier runs.

Is a foot-pound the same as a pound-foot?

For torque, people write it both ways and mean the same thing — a force of one pound acting one foot from the axis. Strictly, "pound-foot" is the torque and "foot-pound" is a unit of energy, but every torque wrench in the shop is marked ft·lb, so that is the label used here.

What is a kilogram-metre of torque?

It is an older metric unit, kgf·m, still printed on some spec sheets and Japanese-market tools. One kgf·m is 9.80665 N·m, because it is the torque from one kilogram of force at one metre. The tool includes it so an old figure and a modern wrench can be matched up.

How many inch-pounds are in a foot-pound?

Twelve, since a foot is twelve inches. Small fasteners are often specced in inch-pounds to avoid tiny decimals — 90 in·lb is 7.5 ft·lb. Enter either and the tool fills in the rest, which saves fumbling the ÷12 on a cold morning.

Torque conversion calculator

These are exact unit conversions of the figure you enter. They do not tell you the right torque for a given fastener — that comes from the spec sheet or the service manual. Always torque to the published value, in the order and sequence it calls for.

Type a torque figure, pick the unit it is written in, and the tool shows the same torque in newton-metres, foot-pounds, inch-pounds and kilogram-metres. Every unit updates live, so matching a metric spec to an imperial wrench takes one glance.

Exemple détaillé

A wheel-nut spec of 100 N·m converts to 100 ÷ 1.35582 ≈ 73.8 ft·lb, or 885 in·lb, or about 10.2 kgf·m. Set your ft·lb wrench to 74 and you have matched the metric figure.

Sur le chantier

A crowfoot on the end of the wrench. The spec is 100 ft·lb, the wrench is 18 in from the centre of the grip to the square drive, and the crowfoot adds 3 in in line with the handle. The fastener sees more than the wrench clicks at: set the wrench to 100 × 18 ÷ (18 + 3) = 85.7 ft·lb. Turn the crowfoot 90° to the handle and the extension is zero — set 100 and click. Measure L and E on your own wrench; nobody's are the same.

Small fasteners live in inch-pounds. A spec of 35 in·lb is 2.9 ft·lb — under the bottom of most foot-pound wrenches' range, where they are not accurate anyway. Use the in·lb wrench. Going the other way, a 20 ft·lb spec on an in·lb wrench is 240; do not let the two get swapped on a cylinder head.

Metric plate, imperial wrench. 90 N·m ÷ 1.356 = 66.4 ft·lb — set 66. 25 N·m is 18.4 ft·lb or 221 in·lb. The wrench does not care which unit the plate used, as long as the number you set is the converted one.

Exercez-vous

Quick referencefor torque

1 ft·lb: 1.356 N·m · 12 in·lb · 0.138 kgf·m
1 N·m: 0.738 ft·lb · 8.85 in·lb · 0.102 kgf·m
Common specs: 50 ft·lb = 68 N·m · 75 = 102 · 100 = 136 · 150 = 203 · 80 N·m = 59 ft·lb · 120 N·m = 89
In-line extension: set = target × L ÷ (L + E) — L grip to drive, E the extension
Extension at 90°: no correction

Mistakes to catchbefore you trust the number

Reading an inch-pound spec as foot-pounds — it is twelve times smaller, and a 100 in·lb fastener at 100 ft·lb strips.
Confusing N·m with kgf·m; the kgf·m figure is about a tenth of the N·m.
Using a crowfoot at 90° and applying the length correction as if it were in line — the in-line correction only applies when the extension adds to the wrench's length.

La formule

N·m = ft·lb × 1.35582 = in·lb × 0.112985 = kgf·m × 9.80665

Everything routes through the newton-metre as the common unit: the entered value is converted to N·m first, then out to each of the others by its own factor. Because every factor is an exact physical definition, the round trip closes to the last digit.

Questions

How do I convert foot-pounds to newton-metres?: Multiply foot-pounds by 1.35582. So 100 ft·lb is 135.6 N·m. Going the other way, divide N·m by that same figure. This tool takes whatever unit you enter and shows all four at once, so you never have to remember which way the multiplier runs.
Is a foot-pound the same as a pound-foot?: For torque, people write it both ways and mean the same thing — a force of one pound acting one foot from the axis. Strictly, "pound-foot" is the torque and "foot-pound" is a unit of energy, but every torque wrench in the shop is marked ft·lb, so that is the label used here.
What is a kilogram-metre of torque?: It is an older metric unit, kgf·m, still printed on some spec sheets and Japanese-market tools. One kgf·m is 9.80665 N·m, because it is the torque from one kilogram of force at one metre. The tool includes it so an old figure and a modern wrench can be matched up.
How many inch-pounds are in a foot-pound?: Twelve, since a foot is twelve inches. Small fasteners are often specced in inch-pounds to avoid tiny decimals — 90 in·lb is 7.5 ft·lb. Enter either and the tool fills in the rest, which saves fumbling the ÷12 on a cold morning.

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