Do I need an impact driver as well as a drill?

What the hammering action actually does, the jobs where it transforms the work, and the ones where it is wrong.

Difficulty: beginner
Time: 12 min
Read: 3 min

Short answer

If you drive long screws — decking, fencing, framing, timber construction — an impact driver is transformative and a drill is not a substitute. For occasional flat-pack and picture hooks, a drill-driver alone is enough.

The two tools look similar and work completely differently. A drill applies steady rotation; an impact driver adds rapid rotational hammer blows when it meets resistance, which is what lets a small tool drive a screw a drill would stall on.

Step by step

Understand the mechanism.When an impact driver meets resistance, an internal hammer strikes the anvil rotationally many times a second. Each blow is a burst of torque, so the tool delivers far more turning force than its size suggests.
Notice what that means for your wrist.The reaction goes into the mechanism rather than into your arm. A drill driving a long screw twists hard in your hand; an impact driver does not, which matters more than the raw speed.
Use it for long screws into timber.Decking, fencing, joists, sheds, structural timber. This is where the difference is dramatic — screws that stall a drill go in steadily and without cam-out.
Keep the drill for drilling.An impact driver takes only hex-shank bits and its hammering is wrong for accurate holes. Twist bits, hole saws, masonry work and anything needing a chuck stay with the drill.
Do not use it for delicate work.Small screws, brass fittings, hinges, electrical accessories, anything into plastic. The torque overwhelms them and strips heads or snaps screws before you notice.
Use Torx or Pozidriv bits, not slotted.Impact-rated bits are made to take the hammering; ordinary bits shatter. Torx grips best and almost never cams out, which is the pairing that makes the tool work properly.
Accept the noise.Impact drivers are loud in a rattling, penetrating way. That is fine outdoors and unpleasant in a flat on a Sunday morning.
Buy into the platform you already own.Bare-tool impact drivers are inexpensive if you already have batteries. Combined drill and impact driver kits are usually better value than either bought separately.
Decide by the work, not the specification.Building anything outdoors, a fence, a deck, a shed: buy one. Hanging pictures and assembling furniture: a drill-driver on a low torque setting is genuinely enough.

Tips

Owning both means never swapping between a drill bit and a driver bit mid-job, which is worth more time than the speed difference.
An impact driver drives long screws into hardwood without pilot holes far more readily than a drill — though pilots are still better near an edge.
Set the drill's clutch low for delicate work rather than reaching for the impact driver. That is what the clutch is for.

Common mistakes

Using an impact driver on small or brass screws — The torque strips the head or shears the screw before you can react. Use a drill with the clutch set low.
Using ordinary driver bits in an impact driver — They are not made for the hammering and shatter, sometimes violently. Use impact-rated bits.

If it doesn't work

Screws snapping when driven

Cause: Too much torque for the screw, or no pilot hole in dense timber — Fix: Pilot-drill in hardwood and near edges, and use a drill with the clutch set appropriately for small screws.

Bit keeps slipping out of the screw head

Cause: Worn bit or a mismatched drive type — Fix: Use a fresh impact-rated bit that matches the screw exactly. Torx cams out far less than Pozidriv.

Drill stalls on long screws

Cause: Resistance beyond what steady rotation can overcome — Fix: This is precisely the case an impact driver solves. Failing that, pilot-drill and use a lubricant such as wax on the thread.

Questions people ask

What is the difference between a drill and an impact driver?

A drill applies steady rotation. An impact driver adds rapid rotational hammer blows when it meets resistance, delivering far more torque for driving screws — but it cannot take standard drill bits and is wrong for delicate work.

Can an impact driver drill holes?

Only with hex-shank bits, and the hammering makes it poor at accurate holes. Keep a drill for drilling and use the impact driver for driving.