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Torque Converter

Convert torque units used in vehicle and bicycle service manuals.

Vehicle specifications use newton-metres, American wrenches are marked in pound-feet, older drawings say kilogram-force metre — on the same bolt, the wrong unit means either a snapped fastener or a loose one. Five common torque units convert in both directions here, all factors derived from their definitions, and the reference table helps build an instinct for what 250 N·m actually feels like.

On conventions: kgf·m is the gravity-based unit, about 9.80665 N·m, while American tools and wrenches use lbf·ft, about 1.3558 N·m. Vehicle specifications quote torque in N·m; an electric motor's torque is large, but the torque at the wheel is further multiplied by the gear ratio, so when comparing specifications, check whether the figure is measured at the motor or at the wheel.

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How to use

  1. Enter the torque and choose its unit.
  2. Read the equivalents in the other units.
  3. Match the unit to the tool or the manual before tightening.
  4. Check whether a vehicle figure is measured at the motor or at the wheel.

How it works

Torque conversion factors

Torque = force x lever arm; the SI unit is the newton-meter (N·m). Based on N·m: 1 kgf·m = 9.80665 N·m, 1 kgf·cm = 0.0980665 N·m, 1 lbf·ft = 1.3558179483 N·m, 1 lbf·in = 0.112984829 N·m.

Why tightening bolts needs the right unit

Service manuals often mix metric and imperial: the same location may say 100 N·m, 10 kgf·m, or 74 lbf·ft. 1 lbf·ft = 12 lbf·in, a 12x gap — the wrong unit can strip threads, cause leaks or loosen components, so convert first, then set the wrench.

Common torque references

Common references: passenger-car wheel bolts about 90-120 N·m; bicycle pedals and stems about 5-35 N·m; spark plugs about 20-30 N·m. Always follow the vehicle/part manual and tighten in a diagonal, staged sequence.

Code example

JavaScript N·m as the hub 

const NM = { nm: 1, kgfm: 9.80665, kgfcm: 0.0980665,
             lbfft: 1.3558179483314, lbfin: 0.112984829 };

const convert = (v, from, to) => v * NM[from] / NM[to];

convert(80, "nm", "kgfm");     // 8.16 (lug nut)
convert(100, "lbfft", "nm");   // 135.6

Python The same coefficients in Python 

NM = {"nm": 1, "kgfm": 9.80665, "lbfft": 1.3558179483314}

convert = lambda v, f, t: v * NM[f] / NM[t]

convert(10, "kgfm", "nm")    # 98.07
convert(25, "nm", "lbfft")   # 18.44

FAQ

What's the difference between torque and force?

Force is the intensity of a push or pull (in N); torque is the turning effect, equal to force times lever arm (in N·m). The same force on a longer wrench gives more torque — the principle behind breaker bars.

How many newton-meters in 1 kgf·m?

1 kgf·m = 9.80665 N·m. A manual's "10 kgf·m" is about 98.1 N·m; conversely 100 N·m is about 10.2 kgf·m. Don't round to 10 for critical bolts — a 2% error can exceed tolerance.

What torque should car wheel bolts use?

Passenger cars are mostly 90-120 N·m (about 9-12 kgf·m), per the service manual. Too little loosens, too much can stretch bolts or damage threads; tighten in a diagonal, staged pattern and ideally use a torque wrench.

How do I switch units on a torque wrench?

Most wrenches label only N·m or kgf·m. If the manual's unit differs, convert here first, then set. Also check it's within the wrench's range — using it beyond range distorts readings or damages it.

What does "torque 250 N·m" in engine specs mean?

The rotational torque output at the crankshaft. To feel the tractive force, roughly divide by wheel radius: a 0.32 m tire radius gives about 780 N of thrust (transmission multiplication aside) — the reason torque affects "how punchy" acceleration is.

Are pound-force foot and pound-force inch easy to confuse?

Very. 1 lbf·ft = 12 lbf·in, a 12x difference. US manuals mostly write lbf·ft, while low-torque spots (throttle bodies, oil-pan screws) may use lbf·in; mixing them often strips threads or causes oil leaks.

Is the conversion process safe?

Yes, and no connection is needed. Conversion runs fully local in the browser; repair parameters you enter aren't uploaded, and history stays on your machine, clearable in one click.