How this calculator works
An inch-pound is a pound-force applied at a one-inch lever arm. The international pound-force is 4.4482216152605 N and one inch is exactly 0.0254 m, so one inch-pound is exactly 0.1129848290276167 N-m. Twelve inch-pounds make one foot-pound because twelve inches make one foot. Both directions of the title question are handled by choosing the input unit.
Formula
N-m = lbf-in x 0.1129848290276167. lbf-in = N-m / 0.1129848290276167. One lbf-ft = 12 lbf-in = 1.3558179483314004 N-m. One N-cm = 0.01 N-m.
Worked example
10 lbf-in = 10 x 0.1129848290276167 = 1.12985 N-m. 5 N-m = 5 / 0.1129848290276167 = 44.2537 lbf-in, which is 3.68781 lbf-ft.
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Frequently asked questions
Are inch-pounds the same as foot-pounds?
No. A foot-pound uses a one-foot lever arm and is twelve times larger than an inch-pound. Torque wrenches for small fasteners are often marked in inch-pounds.
Why is torque not measured in joules if both are force times distance?
Torque is a vector cross product and energy is a scalar dot product. They have the same dimensions but different physical meanings, so the torque unit is written N-m rather than J.
Should I lubricate the thread before using a torque value?
Follow the equipment maker. Lubrication changes the friction under the bolt head and in the thread, so the same torque can produce a different clamp load. These conversions do not change the specified torque.