Calculate the conversion between foot-pounds, inch-pounds, newton-meters, and kgf-m torque units. Convert ft-lb to in-lb by multiplying by 12.
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Torque Conversion Formula
Where ft-lb is the torque in foot-pounds, in-lb is the torque in inch-pounds, and 12 is the number of inches in one foot. To convert foot-pounds to inch-pounds you multiply by 12. To convert inch-pounds back to foot-pounds you divide by 12. The factor is 12 because torque is force times distance, and one foot equals twelve inches, so the same force acts over twelve times the distance.
To move between US and metric torque units, convert through newton-meters using these relationships: 1 ft-lb equals 1.35582 N·m, 1 in-lb equals 0.11298 N·m, and 1 kgf·m equals 9.80665 N·m. You first convert your value into newton-meters and then into the unit you need.
Foot-Pound to Inch-Pound Reference Values
This table lists common foot-pound torque values and their inch-pound and newton-meter equivalents so you can check a result at a glance.
| Foot-pounds (ft-lb) | Inch-pounds (in-lb) | Newton-meters (N·m) |
|---|---|---|
| 1 | 12 | 1.36 |
| 2 | 24 | 2.71 |
| 5 | 60 | 6.78 |
| 10 | 120 | 13.56 |
| 15 | 180 | 20.34 |
| 25 | 300 | 33.90 |
| 50 | 600 | 67.79 |
| 75 | 900 | 101.69 |
| 100 | 1200 | 135.58 |
Example Problems
Example 1. A specification calls for 8 ft-lb of torque, but your torque wrench reads only in inch-pounds. Multiply the foot-pound value by 12: 8 ft-lb times 12 equals 96 in-lb. Set your wrench to 96 in-lb.
Example 2. A small fastener is rated for 45 in-lb and you want the foot-pound figure. Divide by 12: 45 in-lb divided by 12 equals 3.75 ft-lb. The fastener should be tightened to 3.75 ft-lb.
Frequently Asked Questions
How many inch-pounds are in a foot-pound? There are exactly 12 inch-pounds in one foot-pound, because there are 12 inches in one foot and torque scales directly with the length of the lever arm.
Are foot-pounds and inch-pounds the same as pound-feet and pound-inches? For torque they describe the same quantity. Strictly, torque is written as pound-feet (lb-ft) and pound-inches (lb-in), while foot-pounds (ft-lb) and inch-pounds (in-lb) are often used for energy. In everyday tool use the terms are treated as interchangeable, and the 12 to 1 ratio is identical either way.
How do I convert inch-pounds to newton-meters? Multiply the inch-pound value by 0.11298. For example, 100 in-lb times 0.11298 equals about 11.3 N·m. To go from foot-pounds to newton-meters instead, multiply by 1.35582.
