Explainers
Torque units explained: ft-lb, in-lb, Nm, and why listings disagree
One listing says 70 ft-lb, another says 840 in-lb, a third says 95 Nm. Are they the same? This page shows how to convert between the three torque units and why listings for similar tools often disagree, with one real case from a maker's own manual.
On this page
What we compared and why
- One unit for comparison. You can only compare torque in the same unit. We convert everything to ft-lb and show newton-metres beside it.
- The kind of torque. Tightening (max) torque and breakaway (removal) torque are different measurements and must not be compared with each other.
The three units
| From | To ft-lb | To in-lb | To Nm |
|---|---|---|---|
| 1 ft-lb | 1 | 12 | 1.356 |
| 1 in-lb | 0.0833 | 1 | 0.113 |
| 1 Nm | 0.738 | 8.85 | 1 |
So 840 in-lb is 70 ft-lb (840 divided by 12), and 70 ft-lb is about 95 Nm (70 times 1.356). The three figures in the question are the same torque.
Quick rules: divide in-lb by 12 for ft-lb. Multiply ft-lb by about 1.36 for Nm. Divide Nm by about 1.36 for ft-lb.
Why listings for similar tools disagree
- Different kinds of torque. Impact wrenches often list a tightening (max fastening) figure and a higher breakaway figure for loosening. A listing that quotes only the breakaway figure looks stronger than one that quotes only the tightening figure.
- A mode's limit is not the maximum. Some tools have an auto shut-off or precision mode that stops at a low figure. That figure describes the mode, not the tool.
- Rounding across units. A maker that rates a tool in Nm and converts to ft-lb may round differently from one that rates in ft-lb, so two listings for one tool can differ by a few units.
- The listing is simply inconsistent. Sometimes the title says one figure and a bullet another. Our tables then say "Listing gives two values" and use neither.
A real case: one tool, two units
DEWALT's manual for its ATOMIC 1/2-inch impact wrench (DCF921) gives a maximum fastening torque of 300 ft-lb (406 Nm) and a breakaway torque of 450 ft-lb (610 Nm). Check them with the table above:
- 450 ft-lb times 1.356 is 610.2 Nm, which the manual gives as 610.
- 300 ft-lb times 1.356 is 406.8 Nm, which the manual gives as 406, not 407.
The second pair shows the rounding problem in practice: a listing that converts the 300 ft-lb figure itself would print 407 Nm, another that copies the manual prints 406, and both are the same tool. A difference of one or two units after a conversion is rounding, not a different tool. The same manual also shows the first problem in the list above: 300 is a fastening figure, 450 a breakaway figure, so neither may be compared with the other kind on another tool.
How our tables use this
Every torque figure in our tables is converted to ft-lb by us. Where a page also shows Nm, that column is our own conversion. If a listing gives no figure, the cell says so; if it gives two different figures for the same kind of torque, the cell says "Listing gives two values" and we use neither. You can see this on cordless ratchets compared and impact wrenches for lug nuts.
Worked conversions you can reuse
| Figure on a listing | ft-lb | Nm (about) |
|---|---|---|
| 420 in-lb | 35 | 47 |
| 900 in-lb | 75 | 102 |
| 1,825 in-lb | 152 | 206 |
| 60 Nm | 44 | 60 |
| 300 Nm | 221 | 300 |
Each row: in-lb divided by 12 gives ft-lb; ft-lb times 1.356 gives Nm; Nm times 0.738 gives ft-lb.
What this page does not tell you
Torque alone does not tell you which tool suits your work: head size, speed and battery platform matter as much. This page is research-based; we have not measured any tool's torque ourselves.