Torque Converter

Torque converter: convert lb-ft, Nm, kg-m, and in-lb instantly for engine specs, fastener specs, and DIY repairs. Free, private, runs in your browser, no signup.

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Last verified July 2026

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What does this converter do?

Torque converter: convert lb-ft, Nm, kg-m, and in-lb instantly for engine specs, fastener specs, and DIY repairs. Free, private, runs in your browser, no signup.

  • 1 lbf.ft = 1.356 N.m · 1 lbf.in = 0.113 N.m
  • All conversions route through the N.m as the base unit, so every pair of units agrees regardless of which two you enter.
  • Standard factors are shown in the formula panel at the precision the calculator actually uses, so the arithmetic and the panel agree.
Torque conversion example showing 500 N-m as ft-lb and in-lb
500 N-m converts to 368.78 ft-lb and 4425.57 in-lb.

Reference factors (torque)

Factors in terms of the N.m, based on published standard values:

  • 1 lbf.in = 0.112985 N.m
  • 1 lbf.ft = 1.35582 N.m
Formula & evidence

How this calculator works

Reviewed 2026-09-20 · BoringToolsKit Editorial Team

Formula

Torque = value x (newton-metres per source unit), then newton-metres / (newton-metres per target unit). Factors: 1 ft-lb = 1.35582 N.m, 1 in-lb = 0.112985 N.m, so 1 N.m = 0.737562 ft-lb = 8.85075 in-lb. Enter 0 for N.m, 1 for ft-lb, 2 for in-lb.

Worked example

1 lbf.ft = 1.356 N.m · 1 lbf.in = 0.113 N.m

Sources

Sources support the method, terminology, or planning context. Editable assumptions remain your responsibility.

Assumptions to verify

  • Inputs are treated as exact decimal values.
  • Standard (not historical or survey) unit definitions are used.
  • The calculation uses the factors at the precision shown in the formula panel; rounding beyond that is display-only and adds no accuracy.

Frequently asked questions

Why convert through N.m instead of directly?

Routing every unit through a single base (N.m) means each unit needs one factor against the standard, and any pair combines cleanly. Direct pair factors drift apart over time in hand-maintained tables; a base-unit graph cannot.

Where do these exact factors come from?

From published standards (NIST: SP 811 torque conversions). Units like the inch are defined exactly (1 in = 2.54 cm since 1959), so conversions between standard units are exact, not approximate.

How precise is the converted torque value?

The conversion applies the standard factors shown in the formula panel. The practical limit is your input: the result only regroups the number you entered, so digits beyond your original reading do not add accuracy. 3-4 significant figures usually matches what the source measurement knew.

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Cite this tool

BoringToolsKit. “Torque Converter.” boringtoolskit.com/torque-converter/ (reviewed 2026-09-20). Free to reference in articles, syllabi, and answer posts with a link.

Privacy: Inputs and results stay in this browser. Conversion runs locally in your browser; review the output before relying on it.

Worked example: 500 N-m by hand

Take an output flange spec of 500 N-m. Step 1, convert to ft-lb: 500 / 1.35582 = 368.78 ft-lb. Step 2, convert to in-lb: 500 / 0.112985 = 4425.57 in-lb. A sanity check ties them together: since 1 ft = 12 in, ft-lb and in-lb differ by exactly 12, and 368.78 x 12 = 4425.4, which matches to rounding. If your two answers ever disagree by more than about 0.1%, you divided by the wrong factor.

The factors come from base units, not from a table. 1 ft-lb = 1 ft x 1 lb-force = 0.3048 m x 4.44822 N = 1.35582 N-m, and 1 in-lb = 1.35582 / 12 = 0.112985 N-m. That is why the calculator shows 1 N-m = 0.738 ft-lb: it is 1 / 1.35582, rounded. Running the same example in reverse, 368.78 ft-lb x 1.35582 = 500.00 N-m, so the conversion closes on itself with no drift.

Where torque conversions go wrong in practice

The expensive mistake is grabbing the wrong direction of a factor. Spec sheets often list small fasteners in in-lb (spark plugs around 221 in-lb, valve cover bolts 84 to 106 in-lb) and large ones in ft-lb (wheel lugs near 100 N-m = 73.76 ft-lb). If you read 96 in-lb as ft-lb, you apply 12 times the intended clamping force, which is how aluminum threads strip. Using the number-of-units factor 8.85 (N-m to ft-lb is actually 0.738) gives the same 12x-class error.

Precision rules also differ by tool. Click-type torque wrenches are typically rated at 4% accuracy and should be stored unloaded, while a digital adapter rated 2% still inherits the wrench error when stacked. Rounding matters at the low end too: 0.738 ft-lb per N-m is fine for a lug nut, but for an 8 N-m oil-pan spec, 0.737562 versus 0.74 shifts the answer by 0.02 ft-lb, well inside tool tolerance yet easy to avoid by keeping the full factor until the final display.