Inch-Pounds to Foot-Pounds: The 12x Rule Every Mechanic Should Know
By the Super Simple Digital Tools Team · Updated June 2026
If you have ever opened a service manual and found a torque spec in inch-pounds while your wrench reads foot-pounds, you have met the most common reason people search for this conversion. The good news is that it is one of the simplest conversions in all of mechanics, because the two units measure the same thing and are linked by a single whole number: twelve.
Torque is force multiplied by the length of the lever arm it acts on. An inch-pound is one pound of force applied one inch from the pivot; a foot-pound is one pound applied one foot away. Since a foot is exactly twelve inches, moving the same pound of force three, four, or twelve inches further out multiplies the leverage proportionally. That is why one foot-pound is precisely twelve inch-pounds, and why dividing by 12 always gives you the foot-pound answer.
Walk through a few practical numbers. A valve-cover bolt at 89 in-lb works out to about 7.4 ft-lb. A spark plug at 132 in-lb is exactly 11 ft-lb. A bolt at 240 in-lb is a clean 20 ft-lb. Notice how the foot-pound figure is always the smaller-looking number, which is one reason small fasteners are quoted in inch-pounds in the first place: a spec of 89 in-lb is easier to dial in precisely than 7.4 ft-lb.
That precision point matters more than the arithmetic. A torque wrench is most accurate across the middle portion of its range and least reliable at the extremes. Setting a foot-pound wrench to 7 or 8 ft-lb, the very bottom of its scale, invites error, while an inch-pound wrench handles 89 in-lb comfortably in its sweet spot. So even after you convert, the result tells you which tool to grab, not just what to type in.
Use the converter as a sanity check rather than a substitute for the manual. Confirm the figure, confirm the unit your wrench uses, and confirm the wrench's range covers that value with room to spare. Doing all three before you put a wrench on the bolt is what keeps small fasteners from being stripped and large ones from being left dangerously loose.
- To reverse the conversion, multiply foot-pounds by 12: a 25 ft-lb spec equals 300 in-lb.
- If your foot-pound answer falls below about 10 ft-lb, set the value in inch-pounds on an inch-pound wrench for better accuracy.
- Double-check unit abbreviations: lbf-in (or in-lb) is inch-pounds, while lbf-ft (or ft-lb) is foot-pounds, and they are easy to misread.
- Watch for decimals, common specs like 150 in-lb become non-round figures such as 12.5 ft-lb, so do not round the spec down to 12.