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in-lbs, N m and UWO: which drill power numbers can you compare?
Updated
Inch-pounds and newton meters are both torque, so they convert: 1 in-lb is 0.1129848 N m. Unit watts out is a different thing. It is power, and it cannot be turned into a torque number. If two listings use different units, convert the first pair and do not try with the third.
What each listing here shows
| Kit | Power as the listing gives it |
|---|---|
| DEWALT DCD771C2 | 300 UWO in the bullets. The spec table also shows 650 and 530 in-lb |
| Makita XFD131 | 440 in-lb |
| BOSCH PS31-2A | 265 in-lb |
| DEWALT DCD777D1 | 53.1 N m |
| BLACK+DECKER LD120VA | 300 in-lb |
| CRAFTSMAN CMCD711C2 | 280 UWO |
| DEWALT DCK240C2 | 1700 in-lb in the spec table, with no word on which of the two tools it means |
The two that convert
The factor comes from the NIST Guide to the SI: one pound-force inch equals 0.1129848 newton meters. To go from N m to in-lb, divide by it. The DEWALT DCD777D1 listing says 53.1 N m, which is about 470 in-lb. That puts it a little above the Makita XFD131 at 440 in-lb (about 49.7 N m), and well above the BLACK+DECKER at 300 (about 33.9 N m) and the BOSCH at 265 (about 29.9 N m).
- DEWALT DCD777D1 (from 53.1 N m)470 in-lb
- Makita XFD131440 in-lb
- BLACK+DECKER LD120VA300 in-lb
- BOSCH PS31-2A265 in-lb
Keep in mind these are each maker's own maximum torque claims. Makers do not all measure the same way, so treat small gaps as a tie.
The one that does not
DEWALT's support site says the company no longer uses torque to rate its drills and uses unit watts out instead. It describes UWO as the maximum power output of the drill, taken at the point where speed and torque output are highest. A second DEWALT support note is blunt: "We don't disclose torque." CRAFTSMAN uses UWO on its listings here too.
So what about the 650 in-lb and 530 in-lb lines in the DCD771C2 spec table on Amazon? They sit next to a 300 UWO claim in the bullets, and they disagree with each other. DEWALT's own product page gives only the 300 UWO. We go with the maker's page and leave the in-lb lines out of our comparison. The same DEWALT page for the DCD777D1 gives 340 UWO, while its Amazon listing gives 53.1 N m.
How to use UWO
Compare UWO only with UWO. Among the picks here that means 340 for the DCD777D1 (from DEWALT's page), 300 for the DCD771C2 and 280 for the CRAFTSMAN hammer drill. For normal home jobs, all of these and all of the in-lb drills above have enough twist for shelves, hinges and pilot holes. The tool type and the chuck matter more. The checker page has a converter you can type any listing's number into.
Match a kit to your jobs with the drill kit checker, or compare all seven picks on the roundup page.