This educational torque unit converter uses three explicitly labeled units and preserves the printed factor beside the calculation. It converts a supplied torque magnitude; it does not select an equipment setting, calculate a lever force, or certify a measurement.
Keep the quantity and unit together
Support N·m, lbf·ft, and lbf·in. In the latter two, lbf means pound-force, and the dot means multiplication by a length unit. Do not confuse lbf·ft with force divided by length or convert an unlabeled mass-pound value through the same table.
The NIST torque conversion table lists these factors to N·m:
| Source torque unit | Printed factor to N·m |
|---|---|
| lbf·ft | 1.355818 |
| lbf·in | 0.1129848 |
| N·m | 1, identity |
Use the torque-specific quantity category and retain its labels. This helper does not offer joules or a mass-to-torque conversion merely because an expression looks similar.
For a raw source label such as lb-ft, leave conversion unresolved until the quantity and force meaning are confirmed. Keep that raw label in the record alongside the confirmed unit, rather than hiding the clarification behind a silently chosen menu item.
Compare ten foot-units with ten inch-units
For a supplied value x, multiply by the source factor to obtain N·m:
10 lbf·ft × 1.355818 = 13.55818 N·m
10 lbf·in × 0.1129848 = 1.129848 N·m
The same number with a different length unit describes a different torque magnitude. Keep “foot” and “inch” visible beside the input rather than letting both records appear as 10 pounds.
For conversion among the supported units, use canonical factors F and calculate x × F(from) ÷ F(to). The inverse from N·m divides by the selected destination factor. An identity conversion retains the supplied value.
Explain a small difference caused by printed precision
Compare the first example with 120 lbf·in:
120 × 0.1129848 = 13.558176 N·m
10 × 1.355818 = 13.558180 N·m
Difference using the two printed factors: 0.000004 N·m
The foot and inch descriptions correspond through the 12-inch-to-one-foot length relation, but these independently rounded table factors do not produce identical last digits. Their small difference is a precision effect of the selected factor model, not a physical disagreement between the quantities.
Keep the factor exactly as printed for this helper's audit trail. Do not silently substitute more digits in one direction or label a result as exact beyond the source precision. A round trip using one factor model and a comparison across two rounded factors are different checks.
Build a calculation record that can be inspected
Show quantity type “torque magnitude,” raw unit label, confirmed source unit, value, chosen factor, formula, destination unit, and rounding note. For the foot fixture:
Quantity: supplied educational torque magnitude
Confirmed source: 10 lbf·ft
Factor: 1.355818 N·m per lbf·ft, NIST printed value
Result: 13.55818 N·m using that factor
Equipment setting / calibration: not determined
The record is a unit interpretation and arithmetic check. It supplies no force direction, lever-arm angle, equipment rating, safe limit, or calibration evidence. Keep any such source information in its own authorized record.
Distinguish zero, missing, and out-of-scope values
For this bounded interface, accept finite nonnegative magnitudes, with manually typed dot-decimal entries containing a leading digit, up to six fractional places, and a maximum of 1,000,000. Zero is valid. Blank is missing; a negative value is outside this magnitude-only tool, not universally impossible torque.
Require the quantity/unit confirmation before Convert. Reject unknown units, unresolved lb-ft, commas, scientific notation, nonfinite values, or out-of-range entries. Any input or unit edit clears an old result until a valid calculation produces a new record.
Keep the internal calculation unrounded; display up to six decimal places with a rounding indication. Tiny positive outputs below 0.000001 need a less-than label with the unit rather than an apparent zero. Source-factor precision and output formatting are separate limits.
Swap reverses units using the stored unrounded result, then revalidates its range and confirmed quantity basis. Keep a computed input distinct from manually typed text so extra fractional places are preserved; editing it returns to the typing rule. Disable Swap if its result is outside the numeric scope. Reset empties inputs, confirmations, and record; it does not assume a default source unit.
Copyable torque prompt
Create an original educational native torque-unit record and an optional HTML calculator specification with a readable source and test plan. Use supplied torque magnitudes and only N·m, lbf·ft, and lbf·in. A raw lb-ft label requires confirmation that the source means torque and pound-force. Do not guess a mass meaning or offer joule output.
Use NIST's printed canonical factors to N·m: 1, 1.355818, and 0.1129848, respectively. Calculate x × F(from) ÷ F(to); use the same selected factor for inverses and retain identity values. Expected checks: 10 lbf·ft gives 13.55818 N·m; 10 lbf·in gives 1.129848 N·m; 120 lbf·in gives 13.558176 N·m. The 0.000004 difference between the foot and equivalent inch fixtures comes from independently rounded factors, not a physical disagreement. Do not claim unprinted exact digits.
Record the raw label, confirmed quantity and unit, value, factor and source, formula, result unit, and rounding note. Manually typed entries must be finite nonnegative dot decimals with a leading digit, at most six fractional places, and value at most 1,000,000. Zero is valid; blank is missing; negatives are outside this magnitude-only scope. Require confirmed quantity and unit. Reject unknown units, nonfinite values, commas, scientific notation, and out-of-scope entries. Edits or invalid states clear stale output.
Keep the internal result unrounded. Display up to six decimal places with a rounding indication; tiny positive results below 0.000001 need a less-than label and unit. Swap uses the stored unrounded result, reverses units, and revalidates range and quantity. Preserve extra places in a distinct computed input; editing it invokes the manual typing rule. Disable out-of-range Swap with a reason. Label native Convert, Swap, Reset, and status controls. Reset clears units, value, confirmation, and result.
Do not provide equipment settings, lever forces or angles, calibration, safe limits, mass conversion, or certified measurement. Supply a factor, inverse, identity, ambiguity, zero, blank, stale-result, and Swap test matrix. Check keyboard focus, article width, and 360 px width. Mark unexecuted native formulas, code, and runtime checks not_tested. Do not promise storage, export, or host behavior.
Optional use for a prepared conversion record
Keep the supplied quantity and native unit record as the primary material. If you prepare an HTML converter in NOS, its supplied product evidence supports HTML saving and rendering. Verify unit confirmation, factors, and error clearing in the actual workspace before treating that version as tested.
Explore NOS with prepared HTML, keeping pound-force, the length unit, and printed precision beside the result so the converted number retains the meaning of its source.