Every cordless drill spec sheet lists numbers, but the numbers do not all measure the same thing. One drill claims a higher torque figure, another claims a higher power rating, and buyers are left to guess which one will finish the hole faster. The confusion gets worse when someone tries to convert one rating into the other with a single multiplier. The tools for comparing drills start with UWO, RPM, and chuck specs explained side by side, and once you see what each number measures, the comparisons stop feeling arbitrary.
What UWO Measures
UWO stands for unit watts out, a measure of the power output a cordless tool’s motor and drive components can achieve. It describes a drill’s ability to perform work, and it is a function of both torque and speed. Understanding the difference between peak torque vs maximum fastening torque is the first step, because UWO sits on the power side of that divide rather than the force side.
Power as a rate of work
Power is work divided by time. A drill with a higher power rating completes a drilling or driving task faster than an otherwise similar drill with a lower rating, assuming the same bit, material, and technique. A 340 UWO drill will outwork a 280 UWO drill on the same application, which is exactly the comparison the rating was built for. The gap shows up in time to depth, not in the maximum force the tool can apply.
UWO is a relative measure within the brand family that publishes it, because the test conditions stay consistent inside that family. That internal consistency is what makes the number useful for ranking drills from the same manufacturer, and it is also why the number does not transfer cleanly across brands. Treat UWO as a within-family ranking tool, not a universal currency.
Why torque alone misleads
Torque is a measure of turning force, and maximum torque ratings alone lack context. A high-torque drill can stall at low speed, and a lower-torque drill can spin fast enough to finish small holes quickly. The rating that predicts speed of work is power, which combines the two, and that is why some brands publish UWO in the first place. The same reasoning explains why torque figures are published differently across brands and why raw numbers rarely compare cleanly.
Torque, Power, and Speed: The Relationship
The relationship between torque, power, and speed is fixed by physics: power equals torque multiplied by rotational speed, once the units line up. Before comparing brands, it helps to know what each spec means, and the debate over whether Dewalt is a good brand usually stalls on torque numbers that lack the speed context around them.
The power equation
For a rotating system, power and torque relate through speed. Raise the speed at the same torque and power goes up; raise the torque at the same speed and power goes up as well. Gearboxes trade one for the other: a lower gear increases torque at the chuck while cutting speed, and a higher gear does the reverse, all without changing the motor’s power. That trade is the core of every drill design decision.
| Quantity | Common units | What it measures |
|---|---|---|
| Torque | in-lb, ft-lb, Nm | Turning force at the chuck |
| Power | watts, UWO | Rate of doing work |
| Speed | RPM | Rotations per minute of the chuck |
| Energy | battery voltage, Ah | Charge available to the motor |
Notice that torque and power use different units and measure different properties. Multiplying a torque number by a speed number produces a power number, but there is no single conversion factor that turns a published torque rating into a published power rating, because the speed at which each rating was measured varies from tool to tool.
Manufacturers that publish UWO generally do not publish maximum torque for their drills and drivers, which pushes buyers toward the power number as the primary spec. Manufacturers that publish torque often omit power ratings, which pushes the comparison the other way. Either approach works if you stay inside one measurement family; mixing the two is where the confusion starts.
Why UWO Cannot Be Converted to Torque
The idea of a conversion constant between UWO and torque is wrong, because the two quantities sit on different sides of the drivetrain. Knowing how to select cordless drills starts with accepting that power is measured at the motor and torque is measured at the output, and the gearbox between them changes the relationship.
The missing gearbox variable
- Power is measured at the motor and drive components
- Torque is measured at the chuck after gearing
- Gear ratios multiply torque and divide speed
- Different drills use different gear ratios and gear ranges
- No single constant can cover ratios that change per model and per gear setting
Two drills with the same motor power can deliver very different maximum torques if one has a lower first gear. Two drills with the same torque can have very different power ratings if one spins faster. The missing variable is the gearbox, and it is different in every model. Add battery voltage sag, cell quality, and test conditions, and any claimed conversion factor falls apart even faster.
The 340 UWO versus 280 UWO example from earlier helps here. The higher-rated drill is expected to finish work faster because its motor and drive deliver more power, but nothing in either rating says how much torque the chuck will produce in first gear. One model could pair its motor with a low gear for big holes, while another pairs a similar motor with a high gear for speed. Both ratings can be accurate and still tell you nothing about the other quantity.
Comparing Drills Across Brands
Because UWO is used by one family of brands and torque figures are published by others, fair cross-brand comparison means comparing cordless drills on torque, speed, weight, and application fit rather than on a single converted number. No published rating replaces a hands-on test with the battery you actually use.
What to compare instead
- Test with the same battery capacity and state of charge
- Compare chuck size and gear ranges, not just headline torque
- Run the same bit in the same material and time the hole
- Weigh the drill with the same battery installed
- Use UWO only for comparisons within the brand family that publishes it
A drill that wins on paper can lose on site if it runs out of battery, overheats, or sits awkwardly in a gloved hand. Application testing beats spec-sheet conversion every time, and it costs nothing beyond a few minutes with a bit, a block of material, and a stopwatch.
Published numbers also depend on battery state. A drill rated with a fresh premium pack will not produce the same results with a worn standard pack, so any timed test should use the battery you plan to run in daily work. Test the drill the way you will use it.
Higher Voltage Options for Heavy Work
When jobs push past what 18V and 20V packs deliver, 36V cordless drills and hammer drills shift the power question entirely. Higher voltage packs feed more power to the motor, which shows up in both torque and sustained speed on large-diameter holes.
When 36V makes sense
Consider a 36V-class drill for repeated large-diameter holes in concrete, masonry, or steel, where an 18V tool runs hot and drains packs quickly. The trade-offs are weight, cost, and a separate battery platform, so crews that drill big holes daily recover the investment fast, while crews that drill occasionally do not. For those crews, a 20V hammer drill with premium cells may be the better buy.
Voltage classes change the power ceiling. A 36V pack can feed a motor more watts than a 20V pack of similar quality, which is why heavy hammer drills and large hole saws migrate to higher-voltage platforms. The same physics that ties torque, power, and speed together applies at every voltage; only the ceiling moves.
Building a Spec Checklist
The same reading skills apply to every fastening tool on site. Choosing a high-torque impact wrench means reading torque ratings the same way you read a drill’s, and the same questions about gear ratios, test conditions, and battery state apply there too.
Check the numbers that matter
- Confirm what each rating measures: torque, power, or speed
- Look for the test conditions behind the number
- Compare within the same battery platform first
- Match the tool’s duty cycle to your applications
- Verify the rating against a timed real-world test
Once the ratings make sense, the right drill is the one that finishes the work in the time you have, with the battery life you need, in a package your crew will actually carry. UWO and torque both matter; they just answer different questions, and the spec sheet is only the start of the answer.
Keep a short drill log for a few weeks and the patterns appear: which tools stall, which packs sag, which handles get left behind. The numbers explain why, and the next purchase gets easier every cycle.