Impact Wrench vs Impact Driver: What's the Difference?
Updated 2026-09-29
Short answer
Same mechanism, different job. An impact driver has a 1/4 in hex collet for screwdriver bits and is built for screws and small lags. An impact wrench has a square anvil, usually 3/8 or 1/2 in, for sockets and is built for nuts and bolts, with much more torque, published in ft-lbs instead of in-lbs. Screws, get the driver. Lug nuts and seized bolts, get the wrench.
Hex collet or square anvil
Both tools hammer the fastener round with a spinning mass striking an anvil. The difference is what the anvil holds. A driver's is a 1/4 in hex quick-change collet for bits; a wrench's is a square drive for sockets, held on by a friction ring or a detent pin. Anvil types, explained.
Mind the units
Impact drivers publish torque in in-lbs, and the ones here run 1,590 to 2,500. Divide by twelve and that's 133 to 208 ft-lbs. Impact wrenches publish in ft-lbs, and their numbers run into the hundreds.
The 9 impact wrenches here publish fastening torque of 275 to 600 ft-lbs, and nut-busting torque of 590 to 810. Compare fastening with fastening; the nut-busting figure is always the bigger one.
Can one do the other's job?
Sort of. A hex-to-square socket adapter lets an impact driver spin small nuts, and some drivers have a mode for it: the Metabo HPT 36V MultiVolt WH36DC Triple Hammer BOLT Impact Driver lists “5 (Soft, Power, BOLT, BOLT Single, Self-Drilling)”. It's fine for machine bolts and furniture. It is not going to break a rusted lug nut, and the adapter becomes the weak point.
Going the other way works badly. An impact wrench with a hex bit adapter has far too much torque for a screw and snaps bits. Own a driver for screws, and add a wrench when the work turns to cars, trailers or structural bolts.