Torque Converter: Inch-Pounds, Foot-Pounds and N-m

Inch-pounds to foot-pounds and N-m: common values

Divide inch-pounds by 12 for foot-pounds. The last column is the smallest wrench of the three in the range table below whose rated window holds the value, and where it lands on that wrench's scale.

Foot-pounds to inch-pounds and N-m: common values

Multiply foot-pounds by 12 for inch-pounds.

Inch-pounds vs foot-pounds: the 12x mistake

1 ft-lb is 12 in-lb. Divide inch-pounds by 12 to get foot-pounds, or multiply foot-pounds by 12 to go the other way. The mistake is easy to make because the wrong number still looks believable. An 89 in-lb spec is 7.4 ft-lb: set the wrench to 89 ft-lb and it is 12 times too tight, which can snap the bolt or strip the threads it screws into. A 17 ft-lb spec is 204 in-lb: set it to 17 in-lb and it is 12 times too loose. Check the unit printed on the spec and the unit marked on your wrench before you set the collar.

The 20% to 100% rated window of a torque wrench

Most click-type torque wrenches are rated to hold their stated tolerance (typically about plus or minus 4% of the reading, clockwise) only from 20% to 100% of their maximum scale. Makers state this in the manual and on the box, so check yours. Below 20% the accuracy is not specified: the wrench will usually still click, but nobody has promised where. So choose the wrench that puts your number in the middle of its range, never in the bottom tenth. 89 in-lb lands at 45% of a 1/4" 20–200 in-lb wrench, but it is below the bottom of a 3/8" 10–80 ft-lb wrench's scale, because 10 ft-lb is 120 in-lb.

Which torque wrench covers which range

Each window starts at 20% of that wrench's maximum. The printed minimum is where the scale begins, not where the rated accuracy starts. Ratings vary by maker, so check your own wrench's manual.

How do I convert inch-pounds to foot-pounds?

Divide by 12, because 1 ft-lb = 12 in-lb. For example, 89 in-lb is 7.4 ft-lb, 120 in-lb is 10 ft-lb and 200 in-lb is 16.7 ft-lb.

How do I convert foot-pounds to inch-pounds?

Multiply by 12. For example, 17 ft-lb is 204 in-lb, 25 ft-lb is 300 in-lb and 100 ft-lb is 1,200 in-lb.

How do I convert N-m to inch-pounds and foot-pounds?

Multiply N-m by 8.850746 for inch-pounds, or by 0.7375621 for foot-pounds. For example, 10 N-m is 88.5 in-lb or 7.4 ft-lb. Going the other way, 1 ft-lb is about 1.356 N-m and 1 in-lb is about 0.113 N-m.

What is the 12x mistake with torque units?

It is reading a torque in the wrong one of inch-pounds and foot-pounds. The two differ by a factor of 12, so an 89 in-lb spec set as 89 ft-lb is 12 times too tight, and a 17 ft-lb spec set as 17 in-lb is 12 times too loose. Check the unit on the spec and the unit on the wrench before you set it.

Can I use a 3/8" 10–80 ft-lb torque wrench for an 89 in-lb spec?

No. 89 in-lb is 7.4 ft-lb, which is below the 10 ft-lb (120 in-lb) bottom of that wrench's scale, and converting the units does not change that. Use a 1/4" 20–200 in-lb wrench instead: 89 in-lb lands at 45% of its full scale, inside its rated 40–200 in-lb window.

What does the 20% to 100% window on a torque wrench mean?

Most click-type wrenches state their accuracy (typically about plus or minus 4% of the reading, clockwise) only from 20% to 100% of their maximum scale. Below 20% the accuracy is not specified, so pick the wrench that puts your spec near the middle of its range. Ratings vary by maker, so check your wrench's manual.

Which torque wrench do I need for 100 ft-lb?

A 1/2" drive 25–250 ft-lb wrench. 100 ft-lb is 40% of its full scale, inside its rated 50–250 ft-lb window. A 3/8" 10–80 ft-lb wrench tops out at 80 ft-lb, so it cannot reach 100 ft-lb.

Does this converter tell me the torque spec for my bolt?

No. It converts units and checks wrench range; it does not supply a spec. Take the torque from your service manual, or look up your vehicle on WhatSizeBolt, then convert it here if it is written in a different unit from your wrench's scale.

Torque wrenches by range

As an Amazon Associate WhatSizeBolt earns from qualifying purchases. Tool picks are general options, not a fit guarantee for your vehicle or fastener.

• 1/4-Inch Inch-Pound Click Torque Wrench (20–200 in-lb)For specs under about 16 ft-lb: sensors, valve covers, small-engine fasteners. Rated window 40–200 in-lb.LEXIVON 1/4" Drive Inch Pound Torque Wrench, 20–200 in-lb — view on Amazon
• 3/8-Inch Click Torque Wrench (10–80 ft-lb)Spark plugs, drain plugs and brackets. Rated window 16–80 ft-lb.LEXIVON 3/8" Drive Click Torque Wrench, 10–80 ft-lb (LX-182) — view on Amazon
• 1/2-Inch Click Torque Wrench (25–250 ft-lb)Lug nuts, suspension and axle nuts. Rated window 50–250 ft-lb.LEXIVON 1/2" Drive Click Torque Wrench, 25–250 ft-lb (LX-184) — view on Amazon