ConverterHub

Pound-Feet to Newton-Meters Converter

Enter torque in pound-feet to convert to newton-metres.

How it is calculated

The tool takes one torque value in pound-feet and multiplies it by two fixed factors: N·m = lb·ft × 1.3558179 and kgf·m = lb·ft × 0.1382550. The input is a torque (a force times a lever arm), so the unit is pound-force times feet, not a weight. The newton-metre figure is rounded to 2 decimals and the kilogram-force metre figure to 4 decimals. Zero gives zero and a negative number keeps its sign (useful for a reverse-direction torque). The conversion runs one way only, from lb·ft to the metric units. To go from N·m back to lb·ft, divide by 1.3558179.

Worked example

A US service manual gives a wheel-nut torque of 90 lb·ft and your torque wrench is marked in N·m. Step 1: 90 × 1.3558179 = 122.0236, shown as 122.02 N·m. Step 2: 90 × 0.1382550 = 12.44295, shown as 12.4430 kgf·m. Set the wrench to about 122 N·m.

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Common mistakes

  • Entering lb·in (pound-inches) as lb·ft. Small fasteners are often specified in lb·in, and 12 lb·in equal 1 lb·ft, so a value of 120 lb·in must be entered as 10.
  • Reading kgf·m as N·m. The second line is kilogram-force metres, and 1 kgf·m is about 9.8 N·m, so the two numbers are not interchangeable.
  • Confusing torque with engine power. Pound-feet measure twisting force; horsepower or kilowatts measure power, and this tool does not convert between them.
  • Trying to use the tool backwards by typing an N·m figure. It always treats the input as lb·ft, so it multiplies by 1.356 when you needed to divide, and the output is meaningless.

About this calculator

Torque — rotational force — is measured in pound-feet (lb·ft) in US/imperial engineering and newton-metres (N·m) in the metric system, with the conversion 1 lb·ft ≈ 1.35582 N·m (derived from 1 lb-force = 4.44822 N and 1 ft = 0.3048 m). A related unit, kilogram-force metres, is also common on older or non-US spec sheets. You enter a value in lb·ft and the calculator returns it in both N·m and kgf·m; to convert N·m back to lb·ft, divide by 1.35582.

Automotive technicians and mechanical engineers hit this conversion constantly: US car and engine specs (bolt torque, engine torque) are usually quoted in lb·ft, torque wrenches sold internationally are calibrated in N·m, and getting the conversion wrong when tightening a critical fastener — a cylinder head bolt, a wheel lug — can mean a joint that's dangerously under- or over-torqued.

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