Newton-Meters to Inch-Pounds Converter
Convert N·m to in-lb (lb-in) and back for torque screwdrivers, electrical terminals and small motors, with oz-in and cN·m shown alongside.
1 N·m = 8.850746 in-lb · 1 in-lb = 0.112985 N·m
N·m to in-lb Formula
The factor is exact, because 1 in-lb = 4.4482216152605 N × 0.0254 m. A newton-metre is just under 9 inch-pounds. At screwdriver torques the rounding matters, though: 0.6 N·m is 5.31 in-lb, and rounding it to 5 or 6 changes the clamping force by 6–13%.
Torque Screwdriver Settings: N·m to in-lb
The range covered by common adjustable torque screwdrivers, with ounce-inches and centinewton-metres for finer scales.
| N·m | in-lb | oz-in | cN·m |
|---|---|---|---|
| 0.1 N·m | 0.89 | 14.2 | 10 |
| 0.2 N·m | 1.77 | 28.3 | 20 |
| 0.3 N·m | 2.66 | 42.5 | 30 |
| 0.4 N·m | 3.54 | 56.6 | 40 |
| 0.5 N·m | 4.43 | 70.8 | 50 |
| 0.6 N·m | 5.31 | 85 | 60 |
| 0.8 N·m | 7.08 | 113.3 | 80 |
| 1 N·m | 8.85 | 141.6 | 100 |
| 1.2 N·m | 10.62 | 169.9 | 120 |
| 1.5 N·m | 13.28 | 212.4 | 150 |
| 2 N·m | 17.7 | 283.2 | 200 |
| 2.5 N·m | 22.13 | 354 | 250 |
| 3 N·m | 26.55 | 424.8 | 300 |
| 4 N·m | 35.4 | 566.4 | 400 |
| 5 N·m | 44.25 | 708.1 | 500 |
| 6 N·m | 53.1 | 849.7 | 600 |
Worked Example: a 2.5 N·m Breaker Terminal
A DIN-rail circuit breaker made for the IEC market has its terminal torque printed as 2.5 N·m. Your torque screwdriver is scaled in inch-pounds.
Step 1: Multiply by the factor
Step 2: Round to the screwdriver's graduations
Set 22 in-lb. The 0.13 in-lb difference is well under 1%, much finer than a screwdriver's typical ±6% accuracy. If the label gives a range (for example 2–2.5 N·m, or 17.7–22.1 in-lb), aim for the middle.
Electrical Terminals and the NEC Torque Rule
Loose terminal screws cause overheating, and overtightened ones crush conductors or crack housings. Since the 2017 edition, NEC section 110.14(D) has required a calibrated torque tool wherever a manufacturer gives a numeric tightening torque. US equipment usually labels terminals in lb-in, which is the same unit as in-lb. Equipment built to IEC standards uses N·m, and many breakers and panelboards print both.
When a label shows only N·m, convert with the full factor rather than ×9, which overstates by 1.7%. Write both values on your checklist, for example "2.5 N·m (22 lb-in)", so an inspector can see where the number came from.
Motor Torque in N·m and oz-in
Small motor datasheets mix units: European and Asian makers give stepper holding torque in N·m (or mN·m), while US hobby and CNC suppliers often use oz-in. A NEMA 17 stepper rated at 0.45 N·m is 63.7 oz-in, or 3.98 in-lb. When you compare motors, put both figures into the same unit before deciding which is stronger. The converter shows oz-in under every result.
Units Smaller Than an Inch-Pound
| 1 unit | N·m | in-lb | Typically used for |
|---|---|---|---|
| Centinewton-metres (cN·m) | 0.01 | 0.0885 | European precision screwdrivers and instruments |
| Ounce-force inches (oz-in) | 0.007062 | 0.0625 | US small motors, servos and steppers |
| Inch-pounds (in-lb) | 0.112985 | 1 | US torque screwdrivers and terminal labels |
There are 16 oz-in in an inch-pound and 100 cN·m in a newton-metre. Japanese specs in kgf·cm are covered on the inch-pounds to newton-metres page.
Frequently asked questions
What is 2 N·m in inch-pounds?
17.70 in-lb. It is a common terminal and small-screw torque, so set 17.5 or 18 in-lb depending on your screwdriver scale.
How many oz-in are in 1 N·m?
141.6 oz-in. An ounce-inch is 1/16 of an inch-pound, or about 0.00706 N·m.
What is a cN·m?
A centinewton-metre, 0.01 N·m. Precision torque screwdrivers use it to avoid decimals, so 60 cN·m is 0.6 N·m, or 5.31 in-lb.
Is lb-in on an electrical label the same as in-lb?
Yes. Electrical standards and labels usually write lb-in, while tool makers often write in-lb. Both are pound-force × inch.
Sources
- NIST Special Publication 811: exact pound-force, ounce and inch definitions used for the factors.
- NFPA 70: National Electrical Code: section 110.14(D), use of calibrated torque tools on terminals.
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