Impact Driver vs Drill: Which One You Actually Need
If you own one cordless tool, it should be a drill. If you own two, the second should be an impact driver — and the reason is mechanical, not marketing.
How each one delivers torque
A drill/driver spins a chuck through a gearbox with a slip clutch. Torque arrives smoothly and continuously. You control it with the trigger and the clutch setting, which is what you want when a drill bit is cutting.
An impact driver adds a hammer mechanism that strikes rotationally, typically 3,000+ times a minute. Each blow delivers a burst of torque far above what the motor could apply steadily. That is what breaks a seized bolt loose or drives a 100 mm screw into a joist without the tool twisting out of your hands.
The trade-off: those blows are uncontrolled. You cannot feather an impact driver the way you can a drill.
Pick by the job
| Job | Tool |
|---|---|
| Drilling any hole, any material | Drill |
| Hole saws, spade bits, augers | Drill (impact will snap them) |
| Long screws, decking, framing | Impact driver |
| Lag bolts, structural screws | Impact driver |
| Small screws in soft material | Drill, clutch set low |
| Cabinet hinges, hardware, furniture | Drill |
| Seized or rusted fasteners | Impact driver |
| Automotive bolts | Impact wrench (not driver — see below) |
| Mixing paint or thinset | Drill (low speed, high torque) |
| Driving into masonry | Hammer drill |
The bit problem
Impact drivers take 1/4-inch hex shank bits only. Round-shank drill bits do not fit without an adapter, and standard bits are not rated for impact energy — they shatter, and they shatter as fragments.
Anything you put in an impact driver must say “impact rated”. Those bits are made of tougher, slightly softer steel that flexes rather than snapping.
Driver vs wrench, since the names confuse everyone
- Impact driver — 1/4-inch hex, compact, for screws and small bolts.
- Impact wrench — square drive (3/8 or 1/2 inch), takes sockets, far more torque, for wheel nuts and suspension bolts.
An impact driver will not remove a wheel nut torqued to 100 ft-lb. Do not buy one expecting it to.
What to actually buy
One drill: brushless, 18 V/20 V class, two batteries, a 13 mm keyless chuck, and a clutch with real range. Brushless matters more than headline torque — it runs cooler and gets far more work per charge.
Then the impact driver, on the same battery platform. The platform is the real purchase; batteries and chargers outlast the tools and switching brands later is expensive.
Skip the 12 V class if you do outdoor or structural work, and skip the 20-piece “combo kit” whose extra tools are usually the manufacturer’s weakest.
Two habits worth having
- Do not use an impact driver on anything you can overtighten — small machine screws, plastic threads, anything into aluminium. The blows will strip it before you feel resistance.
- Let the drill’s clutch do its job. Setting it high because the screw “needs it” is how you snap screw heads and cam out bit tips.
What the torque numbers mean
Manufacturers quote torque differently for each tool, and comparing the numbers directly is meaningless.
A drill’s figure is stall torque — the rotational force at the moment it stops turning, measured in inch-pounds or Newton-metres. A typical 18 V brushless drill is 450–750 in-lb.
An impact driver’s figure is peak torque delivered in a hammer blow, and a modest one is quoted at 1,500–1,800 in-lb. That is not three times the drill’s capability in continuous use; it is a momentary spike, thousands of times a minute. Continuous torque is much lower.
The practical consequence: an impact driver drives a long screw a drill cannot, and a drill controls a small screw an impact driver will destroy. Neither number tells you that.
Speed settings and why the drill has two
A drill’s gearbox usually offers two ranges:
- Low (1) — around 0–500 rpm, maximum torque. For large-diameter holes, hole saws, augers, mixing, and driving big fasteners.
- High (2) — around 0–1,800 rpm, less torque. For small twist bits in wood and metal, where cutting speed matters.
Using high range for a 50 mm hole saw is the most common cause of a drill overheating, and of the bit grabbing hard enough to twist the tool out of your hands. Change the range rather than pulling the trigger harder.
Chuck types
Keyless chucks dominate and are fine. Two habits keep them working: tighten by gripping the chuck and running the motor briefly in a low gear, and when a bit slips, clean the jaws rather than gripping harder.
A 13 mm (1/2 inch) chuck is worth having over a 10 mm one — it takes larger shank bits and hole saw mandrels.
Impact drivers have no chuck — a 1/4-inch hex collet that accepts bits with a single click. Faster to change, and it will not hold a round shank at all.
Batteries, honestly
The battery is most of the tool’s cost over its life, and the platform is the real decision. Some guidance that holds across brands:
- Amp-hours are runtime, not power. A 5.0 Ah pack runs longer than a 2.0 Ah pack; it does not make the tool stronger. It is also noticeably heavier, which matters for overhead work.
- Two small packs beat one large pack for most people — you always have a charged one.
- Do not store them empty or in a freezing garage. Lithium cells degrade fastest at very low charge and at temperature extremes.
- The platform outlives the tools. Choose a brand with the range you will eventually want, because switching later means buying batteries again.
A realistic buying order
- Brushless drill/driver, 18 V class, 13 mm chuck, two batteries.
- Impact driver on the same platform, once you meet a screw the drill struggles with. That happens sooner than people expect if you do any decking, framing, or outdoor work.
- Impact wrench only if you work on cars.
- Hammer drill or rotary hammer only if you drill masonry regularly — a hammer-drill function on a combi drill is adequate for occasional holes in brick and useless for concrete.
Buying the three-tool combo kit up front usually means paying for a torch and a weak circular saw you will replace. The drill first, then buy against actual need.