Inch-Pounds to Foot-Pounds Converter

Some torque wrenches are marked in inch-pounds, others in foot-pounds, and many service manuals use whichever scale makes the number easiest to read. This converter handles the pound-based pair without adding metric factors. It is most useful when a small fastener specification is written as in-lb, lb-in, or inch-pounds-force, but the available wrench displays ft-lb, or when a foot-pound value must be rewritten for a low-range inch-pound driver. The relationship is exact because the force unit is unchanged and the distance unit changes from inches to feet.

Torque equals force times the perpendicular distance from the pivot. In inch-pounds, the distance is inches. In foot-pounds, the distance is feet. Since one foot is exactly 12 inches, one ft-lb is exactly 12 in-lb. That makes this page different from the Nm to ft-lbs converter and Nm to in-lbs converter, where the force system changes too. Here, the main risk is not an obscure constant; it is using the wrong direction and being off by twelve.

Using the two directions

The form defaults to in-lb to ft-lb and starts with 120 in-lb. The calculator divides that value by 12, so the primary result is 10 ft-lb. Switch the segmented control to ft-lb to in-lb when the source value is already in foot-pounds. In that mode, the default 10 ft-lb is multiplied by 12 and returns 120 in-lb.

Choose the direction before entering the number. Moving from inch-pounds to foot-pounds makes the displayed number smaller because feet are larger than inches. Moving from foot-pounds to inch-pounds makes the displayed number larger. If the converted foot-pound result is below your wrench’s reliable range, use an inch-pound wrench instead of forcing the setting onto a coarse tool. For a broader list of torque units, use the torque converter.

Formula

For inch-pounds to foot-pounds:

$\text{torque in ft-lb} = \frac{\text{torque in in-lb}}{12}$

For foot-pounds to inch-pounds:

$\text{torque in in-lb} = \text{torque in ft-lb} \cdot 12$

The formulas assume torque units based on pound-force. If a document is using pound-mass in a nonstandard way, resolve that context before applying a wrench setting.

Conversion example from the calculator

The default in-lb to ft-lb mode uses 120 in-lb. The calculation is:

$\frac{120\ \text{in-lb}}{12} = 10\ \text{ft-lb}$

The result panel therefore shows 10 ft-lb, with the factor line stating 1 ft-lb equals 12 in-lb. In the reverse mode, the default value is 10 ft-lb:

$10\ \text{ft-lb} \cdot 12 = 120\ \text{in-lb}$

Those two examples are the same torque expressed with different lever-arm units. They should tighten the same fastener only if the wrench is accurate at that setting and the original specification calls for that torque.

Reference table for shop values

The table shows common conversion checkpoints, not universal fastener specifications. Confirm the actual value from the drawing, service manual, or product label.

Why the lb-ft and lb-in distinction matters

Foot-pounds, pound-feet, inch-pounds, and pound-inches can all appear in manuals. In torque context, the order of the words does not change the multiplication of force and lever arm, but the length unit absolutely changes the number. A label of ft-lb belongs to a scale twelve times larger than in-lb. This matters most near the boundary between small and medium fasteners: valve covers, pan bolts, sensor retainers, small brackets, bicycle stems, and appliance or machinery panels. A number that looks moderate in inch-pounds may be too small for a foot-pound wrench to set accurately.

For metric service information, use the inch-lbs to Nm converter or the newton meter calculator. For force-only conversions, the force converter is related but separate: torque requires both a force and a lever arm.

Pitfalls to avoid

Do not shorten inch-pounds to pounds. Pounds alone do not describe torque because they omit the lever arm. Do not assume a foot-pound number can be copied onto an inch-pound wrench. Do not ignore the low-end accuracy of a torque wrench; many click-style tools are least reliable at the bottom of their range. Do not confuse torque with energy even though foot-pound can also appear in energy discussions. In this page, the quantity is a twisting moment used for fasteners and rotating systems, not work done along a path.

Sources

• NIST, SI units — background on coherent unit systems and derived SI units.
• NIST, The NIST Reference on Constants, Units, and Uncertainty: SI units — unit reference material for force, length, and derived quantities.
• NIST, Handbook 44, Appendix C — exact 12-inch-per-foot relationship used by the converter.