Torque Converter

What is torque?

Torque is a twisting force — how hard something is rotated around an axis. It is force times the distance from the pivot: torque = force × lever arm. You feel torque when you tighten a bolt with a wrench, twist a screwdriver, or feel an engine's pulling power. The newton-meter (N·m) is the SI unit: one newton of force applied one meter from the axis. Because torque carries both a force and a length, its units look like "force × distance," which is why we have N·m, ft·lb, kg·m, and in·lb.

Why several torque units?

Engineering and automotive manuals split along metric/imperial lines. European and Asian vehicles spec bolt and lug-nut torque in N·m; older or American manuals use foot-pounds; some workshops still quote kilogram-meters (a gravitational unit); small fasteners and bicycle components are often listed in inch-pounds. A torque converter lets you set your wrench correctly no matter which unit the spec uses — critical, because over- or under-tightening a bolt can cause failure.

The base-unit method

We convert every value into newton-meters (the base) via each unit's N·m factor, then divide by the target factor. This is simple multiplication/division and is exact to six decimals. For example, 1 ft·lb = 1.35581795 N·m and 1 in·lb = 0.11298483 N·m, so 1 ft·lb = 12 in·lb. The tool computes any pair instantly.

Key conversion factors

• 1 newton-meter = 1 N·m (base)
• 1 foot-pound = 1.35581795 N·m
• 1 inch-pound = 0.11298483 N·m (12 in·lb = 1 ft·lb)
• 1 kilogram-meter = 9.80665 N·m

N·m vs ft·lb — the everyday swap

The conversion you will use most: 1 N·m = 0.737562 ft·lb, and 1 ft·lb = 1.355818 N·m. So a wheel spec of 120 N·m is about 88.5 ft·lb; a 100 ft·lb spec is about 135.6 N·m. Because the factor is close to 3/4 and 4/3, many mechanics approximate "N·m ÷ 1.356 = ft·lb," but the exact value avoids small errors that matter on critical fasteners.

Kilogram-meter vs newton-meter

The kilogram-meter (kg·m, sometimes written kgf·m) is a gravitational unit: one kilogram of force (9.80665 N) at a one-meter arm. So 1 kg·m = 9.80665 N·m. It is still seen in older metric literature and some motorcycle specs. Don't confuse it with the newton-meter — they differ by the gravitational constant g, a factor of about 9.8. Our tool keeps both clearly labeled.

Real-world examples

A car's lug nuts are often 100–120 N·m (74–88 ft·lb). A cylinder-head bolt might be 60 N·m = 44.3 ft·lb. A bicycle crank bolt could be 40 N·m = 354 in·lb. An engine's peak torque of 250 ft·lb = 338.9 N·m. A small electrical enclosure screw might be 20 in·lb = 2.26 N·m. Matching the correct number to your wrench's scale prevents stripped threads and broken bolts.

Common mistakes

The first mistake is mixing up N·m and kg·m — off by nearly 10×, a dangerous error on a fastener. The second is confusing foot-pounds (torque) with foot-pounds (energy); they share notation but are different quantities — torque is a twist, energy is work, even though both can be written ft·lb. The third is forgetting that 12 in·lb = 1 ft·lb, so a spec in inch-pounds is much smaller numerically than the same torque in foot-pounds. Use the converter to keep units unambiguous.

Frequently asked questions