Power tools
Impact driver vs hammer drill: which one do you actually need?
They do different jobs. A hammer drill makes holes in masonry. An impact driver drives screws and bolts with high torque and cannot hold a round drill bit. If you are fixing into concrete, buy the hammer drill. If you are driving hundreds of screws, buy the impact driver. Most trades end up owning both.
5 min read · updated 28 July 2026
These two tools look similar, cost about the same, and are constantly confused. They share almost nothing mechanically.
Side by side
| Hammer drill | Impact driver | Rotary hammer (SDS) | |
|---|---|---|---|
| What it does | Vibrates the chuck forward while rotating | Delivers rotational hammer blows | Piston strikes the bit directly |
| Chuck | 13 mm keyed or keyless | 1/4" hex collet only | SDS-Plus / SDS-Max |
| Primary job | Holes in block and light concrete | Driving screws and bolts | Holes in reinforced concrete, chiselling |
| Typical price in Kenya | KES 3,800–14,000 | KES 9,000–24,000 | KES 15,000–45,000 |
| Buy it if | You fix into walls occasionally | You drive fixings all day | You drill concrete daily |
Why the impact driver surprises people
The torque goes into the fixing rather than into your wrist. A 100mm coach screw goes into timber without a pilot hole and without the tool trying to twist out of your hand. Roofers, deck builders, timber framers and solar installers use them constantly and rarely go back.
The limitation is precision. The impact mechanism will strip a small screw head, crack a plastic fitting, or snap a thin brass screw before you have noticed. Keep a drill-driver with a clutch for delicate work.
Why the rotary hammer changes concrete work
A hammer drill vibrates the whole chuck assembly. A rotary hammer drives a piston that strikes the bit directly, so far more of the energy reaches the hole. A 10mm hole through a reinforced slab takes seconds instead of a minute of leaning on a hammer drill.
If you set anchors or chase walls for conduit every day, this is the tool that pays for itself fastest — and it is the one most people delay buying for too long.
The buying order
- A combi drill, which drills, drives and has a hammer setting for occasional masonry.
- An impact driver, once you are driving enough fixings to feel it in your wrist.
- An SDS rotary hammer, once concrete is a daily part of the job.
Common questions
Can an impact driver be used as a drill?
Only with hex-shank drill bits, and not for accurate work. The 1/4-inch collet will not hold a round shank, and the impact action makes it hard to start a hole precisely. Keep a drill for drilling.
Can a hammer drill drive screws?
Yes, with the hammer action switched off and the clutch set appropriately. It is slower and harder on your wrist than an impact driver, but it works.
Why do my screwdriver bits keep snapping in my impact driver?
Standard bits are too hard and fracture under impact loads. Use impact-rated bits, which are made from a more ductile steel that twists rather than shatters.