Last Updated: February 2026
That spec sheet has 15 numbers on it. RPM, IPM, UWO, torque in three different units, no-load speed, clutch settings… and somehow you’re supposed to figure out which tool is better from all that.
Here’s the thing: most of those numbers matter — but only if you know what they actually mean in practice. A tool with 1,400 in-lbs of torque sounds impressive until you realize you’ll never use half of it driving deck screws. And that “2,100 RPM” on the box? That’s measured with nothing in the chuck.
This guide translates every major power tool spec into plain language. Bookmark it. You’ll be back.
RPM (Revolutions Per Minute)
What it measures: How fast the chuck (or blade) spins. One revolution = one full rotation.
RPM is the most straightforward spec on any tool. Higher RPM means the bit or blade spins faster. But faster isn’t always better — in fact, running too fast is one of the most common mistakes DIYers make.
Why Variable Speed Matters
A drill with a single fixed speed is nearly useless for real-world work. Different materials and fasteners demand different speeds:
- Drilling into metal: Slow — 300-800 RPM. High speed generates excessive heat that dulls bits and hardens the workpiece.
- Drilling into wood: Fast — 1,000-2,000 RPM. Wood is forgiving, and higher speed means cleaner holes with less tear-out.
- Driving screws: Slow and controlled — 400-800 RPM. Too fast and you’ll strip the head, overdrive the screw, or split the wood.
- Drilling masonry (hammer mode): Moderate — 800-1,500 RPM. The percussion does the work, not the rotation speed.
Most modern drills have a two-speed gearbox. Speed 1 (low range) gives you more torque at lower RPM — ideal for driving screws and drilling large holes. Speed 2 (high range) gives you maximum RPM for drilling smaller holes quickly.
The practical takeaway: Don’t buy a drill based on max RPM alone. A drill with 2,000 RPM and good variable speed control will outperform a 2,500 RPM drill with jerky trigger response every time. For a real-world comparison, see our best cordless drills roundup.
IPM and BPM (Impacts and Blows Per Minute)
What they measure: The rate of percussive strikes delivered by the tool’s internal mechanism. Here’s where things get confusing — because impact drivers and hammer drills both use “impacts per minute,” but they work in completely different ways.
Impact Drivers: Concentric (Rotational) Impacts
An impact driver delivers rotational blows around the axis of the bit. Think of it like a hammer hitting a wrench to break a stubborn bolt loose — the impacts add bursts of rotational force (torque) beyond what the motor alone can produce.
- Typical range: 3,000-4,400 IPM
- Higher IPM = smoother driving feel, less vibration per impact
- The impacts engage automatically when resistance exceeds the motor’s direct drive capability
Hammer Drills: Axial (Percussive) Blows
A hammer drill delivers forward-and-back blows along the drill’s axis — like a tiny jackhammer behind the bit. This pulverizes concrete and masonry so the rotating bit can clear debris.
- Typical range: 28,000-38,000 BPM
- Higher BPM = faster drilling in masonry
- The blows are much lighter than a rotary hammer but happen at extremely high frequency
Why You Can’t Compare Them
A hammer drill at 34,000 BPM and an impact driver at 4,000 IPM are measuring completely different things. The hammer drill delivers thousands of tiny forward blows per minute. The impact driver delivers far fewer but much more powerful rotational strikes. Comparing these numbers across tool types is meaningless — like comparing a car’s RPM to its horsepower.
For more on how impact drivers use these specs in practice, check our best impact drivers guide.
Torque (in-lbs, ft-lbs, N·m)
What it measures: Rotational force. How hard the tool can twist. This is the spec most people fixate on — and the one most people misunderstand.
Max Torque vs. Working Torque
The torque number on the box is maximum torque — the absolute peak the tool can deliver under ideal lab conditions. In practice, you’ll never sustain that number. Working torque (what you get during continuous operation) is typically 30-50% lower.
Some manufacturers publish “tested” or “measured” torque values that are closer to real-world performance. These are far more useful for comparison than the headline spec.
Conversion Table
| From | To | Formula | Example |
|---|---|---|---|
| in-lbs | ft-lbs | ÷ 12 | 1,200 in-lbs = 100 ft-lbs |
| ft-lbs | in-lbs | × 12 | 100 ft-lbs = 1,200 in-lbs |
| N·m | in-lbs | × 8.85 | 150 N·m = 1,328 in-lbs |
| in-lbs | N·m | ÷ 8.85 | 1,200 in-lbs = 135.6 N·m |
| N·m | ft-lbs | × 0.738 | 150 N·m = 110.6 ft-lbs |
| ft-lbs | N·m | × 1.356 | 100 ft-lbs = 135.6 N·m |
How Much Torque Do You Actually Need?
| Task | Torque Needed |
|---|---|
| IKEA furniture assembly | 50-100 in-lbs |
| Driving deck screws (softwood) | 200-400 in-lbs |
| Driving lag bolts | 500-1,000 in-lbs |
| Automotive lug nuts | 80-100 ft-lbs (960-1,200 in-lbs) |
| Drilling 1″ holes in hardwood | 600-900 in-lbs |
| Heavy structural bolting | 150+ ft-lbs (1,800+ in-lbs) |
Most cordless drills deliver 500-1,400 in-lbs of max torque. Most cordless impact drivers deliver 1,500-2,400 in-lbs. For everyday home projects, any modern 18V/20V drill has more torque than you’ll ever use. The differences matter most at the extremes — large lag bolts, long structural screws, and hole saws in hardwood.
UWO (Unit Watts Out)
What it measures: Actual mechanical power delivered at the chuck, measured in watts. This is a DeWalt-specific metric, and it’s actually one of the more useful specs in the industry — if you understand what it is and what it isn’t.
Why UWO Exists
Torque tells you how hard a tool can twist. RPM tells you how fast it spins. But neither tells you the full story about a tool’s real-world power output. UWO combines both into a single number that represents actual usable power — watts measured at the tool’s output, not at the motor.
The formula is straightforward: Power (watts) = Torque × Speed. UWO captures this relationship at the point that matters — the chuck, after all the drivetrain losses.
How to Use UWO
UWO is most useful for comparing DeWalt tools to each other. A drill rated at 750 UWO will meaningfully outperform one rated at 500 UWO in sustained work — boring large holes, mixing compounds, or driving long screws into dense material.
The catch: you can’t directly compare UWO across brands. Other manufacturers don’t publish this metric, and there’s no standardized test protocol across the industry. Makita, Bosch, and others publish torque and RPM separately, which theoretically lets you calculate power — but the testing conditions and measurement points differ enough that direct comparison is unreliable.
What to look for instead: When comparing across brands, focus on independent benchmark tests that measure actual performance — things like “time to drive 50 screws” or “holes drilled per charge.” Those real-world numbers tell you more than any single spec.
Clutch Settings
What they are: The numbered dial on a drill/driver (typically 1 through 20 or higher) that controls how much torque the tool delivers before the clutch disengages and the chuck stops spinning.
How the Clutch Works
When the resistance on the bit exceeds the clutch setting, the clutch “slips” — the motor keeps running but the chuck stops turning. You hear that distinctive clicking/ratcheting sound. This prevents:
- Stripped screw heads — the bit stops turning before it destroys the screw
- Overdriven screws — the screw stops at the right depth instead of burying into the material
- Cam-outs — the bit stays engaged instead of jumping out and gouging your workpiece
- Wrist injuries — the clutch absorbs the reaction force instead of your arm
What the Numbers Mean
| Setting Range | Torque Level | Best For |
|---|---|---|
| 1-5 | Low | Small screws in soft materials (drywall, thin plywood, MDF) |
| 6-10 | Medium-Low | Cabinet screws, hinge screws, medium fasteners in softwood |
| 11-15 | Medium | Deck screws, general construction fasteners |
| 16-20+ | High | Large screws in hardwood, lag bolts, dense materials |
| Drill icon | No clutch (max) | Drilling holes only — never for driving screws |
Pro tip: Start with a lower clutch setting than you think you need and work up. It’s much easier to add one more click of torque than to patch a stripped screw hole. Most drywall work sits around 3-5. Deck screws in pressure-treated lumber usually need 12-16.
No-Load Speed vs. Under-Load Speed
What it means: The RPM and IPM numbers on every spec sheet are measured with nothing in the chuck. The tool is just spinning freely in the air. That’s the “no-load” speed.
The moment you push a bit into wood, metal, or concrete, the speed drops. How much it drops is what separates good tools from great ones.
Why This Matters
Two drills can both advertise 2,000 RPM no-load speed. Under load — actually drilling into lumber — one might sustain 1,600 RPM while the other drops to 1,100 RPM. The first drill will bore holes faster, run cooler, and finish the job with more battery left.
This is where brushless motors earn their price premium. Brushless designs maintain speed under load far better than brushed motors because the electronic controller actively adjusts current to compensate for increased resistance. A brushless drill maintaining 85% of its no-load speed under moderate load is typical. A brushed drill might only maintain 60-70%.
What to Look For
Manufacturers rarely publish under-load numbers. Look for:
- Independent reviews with test data — reviewers who measure actual drilling speed with a tachometer
- “Constant speed” or “speed management” features — electronic load compensation that actively maintains RPM
- Brushless motor — inherently better at maintaining speed under load
- Higher amp-hour batteries — provide more current to maintain speed when the motor demands it
Bottom line: A 1,800 RPM brushless drill that holds its speed under load will outperform a 2,200 RPM brushed drill that bogs down as soon as it hits a knot. Don’t buy on no-load numbers alone.
Cutting Specs for Saws
Saws have their own language. Here’s what each spec actually tells you about capability.
Blade Diameter
The blade size determines the maximum depth of cut. Bigger blade = deeper cut, but also heavier tool and more battery drain.
| Blade Size | Max Depth (at 90°) | Common Use |
|---|---|---|
| 5-3/8″ | ~1-5/8″ | Trim work, thin sheet goods — compact saws |
| 6-1/2″ | ~2-1/8″ | Most framing and general cuts — won’t rip a full 2x in one pass |
| 7-1/4″ | ~2-7/16″ | Full framing capacity — cuts through a 2x at 90° and 45° |
For cordless circular saw comparisons, check our best cordless circular saws guide.
Arbor Size
The hole in the center of the blade. This must match your saw. Most full-size circular saws use a 5/8″ arbor. Some compact saws use smaller arbors. Using the wrong arbor size means the blade won’t mount — or worse, it wobbles dangerously.
Bevel Capacity
How far the blade tilts for angled cuts. Standard is 0-50° or 0-56°. A saw with bevel capacity can cut angles for roof rafters, stair stringers, and trim joints without a miter saw. More bevel range = more versatility, but most work happens at 0° and 45°.
Miter Range (Miter Saws)
How far left and right the blade swings. A miter saw with 0-50° left and 0-60° right covers virtually every trim angle you’ll encounter. Dual-bevel miter saws tilt both directions, eliminating the need to flip the workpiece. For a comparison of the best options, see our best miter saws roundup.
Depth of Cut
The maximum thickness of material the saw can cut in a single pass. Always check the depth at both 90° (straight cut) and 45° (bevel cut). The 45° number is always significantly less. If you’re regularly cutting 4×4 posts, you need a saw with at least 3-1/2″ depth of cut at 90° — and that means a 10″ miter saw or a 7-1/4″ circular saw with a careful two-pass approach.
Weight and Ergonomics
Why this spec matters more than most people think: A drill that weighs 4.5 lbs feels fine for the first 10 screws. After 200 screws on a deck build, every ounce matters. Fatigue kills precision and increases injury risk.
Head Weight vs. Total Weight
The number on the spec sheet is total weight — tool body plus battery. But what matters for fatigue and control is head weight (the weight forward of your grip). A tool with more weight concentrated in the head feels heavier and is harder to control overhead, even if the total weight is similar to a better-balanced competitor.
This is why compact drills have become so popular. A 1.5 lb reduction doesn’t sound dramatic until you’ve spent four hours driving screws overhead while installing subfloor from below.
What to Look For
- Bare tool weight vs. with battery: Spec sheets sometimes list bare tool weight (without battery). Always compare with the same battery size.
- Length: Shorter tools fit into tight spaces — between joists, inside cabinets, behind pipes. A drill that’s 6.5″ long vs 8.5″ long makes a real difference in tight work.
- Grip circumference: Larger hands need larger grips. If you can’t comfortably wrap your hand around the grip, you’ll fatigue faster and lose control.
- Balance point: Pick up the tool with one finger under the handle. Does it tip forward dramatically? That’s a front-heavy tool. Better-balanced tools are easier to control, especially for overhead work.
Quick Reference: All Specs at a Glance
| Spec | What It Measures | What to Look For | Common Pitfall |
|---|---|---|---|
| RPM | Rotation speed | Variable speed with smooth trigger | Assuming higher is always better |
| IPM | Rotational impacts (impact drivers) | 3,200+ IPM for smooth driving | Comparing IPM to BPM |
| BPM | Axial blows (hammer drills) | 28,000+ BPM for masonry work | Comparing BPM to IPM |
| Torque (in-lbs) | Rotational force | 500+ in-lbs for general use | Comparing max torque across brands without context |
| UWO | Power at the chuck (DeWalt only) | Higher UWO = more sustained power | Trying to compare UWO to other brands’ torque |
| Clutch Settings | Torque limit before slip | 15+ settings for fine control | Leaving it on drill mode for driving screws |
| No-Load Speed | Free-spinning RPM | Brushless motor for speed retention | Assuming no-load speed = working speed |
| Blade Diameter | Cutting capacity | 7-1/4″ for full 2x capacity | Forgetting to check 45° depth of cut |
| Arbor Size | Blade mounting hole | 5/8″ standard for full-size saws | Buying blades with wrong arbor size |
| Weight | Total tool mass | Under 5 lbs with battery for drills | Ignoring weight for all-day use |
Frequently Asked Questions
Is higher torque always better?
No. More torque than you need just means more potential to strip screws, overdrive fasteners, and break bits. A 1,400 in-lbs drill and a 700 in-lbs drill will both drive deck screws equally well — the job only requires about 300 in-lbs. Where extra torque matters is large-diameter holes (hole saws, spade bits in hardwood) and heavy fasteners (lag bolts, structural screws). For everyday home use, any modern 18V drill has sufficient torque.
Why do some drills have two speed settings?
Two-speed drills use a mechanical gearbox — the same concept as low gear and high gear in a car. Speed 1 (low range) reduces RPM but increases torque, ideal for driving screws and drilling large holes. Speed 2 (high range) maximizes RPM for drilling smaller holes quickly. The switch is usually a slider on top of the tool. Always use Speed 1 for driving screws — Speed 2 spins too fast for controlled fastening.
What’s the difference between IPM and BPM?
IPM (impacts per minute) measures rotational strikes in an impact driver — they add torque around the bit axis. BPM (blows per minute) measures axial strikes in a hammer drill — they push the bit forward into masonry. Different mechanisms, different purposes, different scales. An impact driver at 4,000 IPM and a hammer drill at 34,000 BPM cannot be meaningfully compared.
Can I compare specs across brands?
With caveats. Torque values use the same units (in-lbs, N·m) but testing conditions vary — some brands measure at the motor, others at the chuck, and “max” vs “continuous” definitions differ. RPM is the most directly comparable spec since it’s a straightforward measurement. UWO is DeWalt-only. Weight is reliable if you compare with the same battery type. For the most accurate cross-brand comparisons, look at independent head-to-head tests rather than spec sheets.
What does “brushless” mean for specs?
A brushless motor uses electronic commutation instead of physical carbon brushes. The spec sheet impact: brushless tools maintain closer to their advertised speed under load, run cooler (extending battery life by 20-50%), produce more torque per watt of input, and last longer because there are no brushes to wear out. Virtually every premium cordless tool sold today is brushless. If you see a suspiciously cheap price on a drill, check whether it’s brushed — that’s usually why.
Specs tell you what a tool can do. Reviews tell you how well it does it. Pair this guide with our tool roundups to make smarter buying decisions: drills, impact drivers, circular saws, and miter saws.
