Best impact driver bit sets: Milwaukee, DeWalt, Makita and Bosch compared by contents

01What should an impact driver bit set have?

A set for an impact driver should contain impact-rated bits, the drive types and sizes you meet most often, a mix of short insert bits and longer power bits, and a holder that keeps screws on the bit. Each point below explains why it matters.

Impact rating and a torsion zone

Impact-rated bits have a torsion zone, a section of the shank designed to absorb the torque peaks an impact driver delivers, so the tip does not break or wear early. Wera calls it TZ, Milwaukee calls it SHOCKZONE, DeWalt calls its version FlexTorq and Bosch calls its version the Xtended Torsion Zone. Standard bits share the same hex shank, but the screwdriver-bit reference behind this page notes that their harder heat treatment is more brittle, so they tend to fail early in an impact driver.

Hex shank: one size for every brand

Driver bits for drills, impact drivers and bit holders use a 1/4 in hexagonal shank, defined internationally in ISO 1173. Every impact driver in our tool data takes it: DeWalt DCF845 lists a 1/4 in hex chuck, Milwaukee 2953-20 lists 1/4 in, and Ryobi PBLID01 lists 1/4 in. A Bosch set therefore fits a Milwaukee driver, and a Makita set fits a DeWalt. The full explanation of shank forms is on our page about what fits an impact driver.

Insert bits and power bits

Short insert bits sit in a magnetic or quick-release bit holder; Wera gives the common insert length as 25 mm. Longer power bits, commonly 2 in, lock directly into the driver's quick-change chuck and reach into recesses. A useful set has many of the drive you use most as insert bits and a few power bits for reach.

Drive types: match the screws you buy

Phillips (PH), Pozidriv (PZ), Torx (T or TX), square or Robertson (SQ or R) and slotted (SL) are the common drives. Torx and square drives are regarded as resisting cam-out better than Phillips. Pozidriv screws carry tick marks at 45 degrees between the main slots and need PZ bits.

02Does the bit set have to match your impact driver's brand?

No. The hex shank is a cross-brand standard, so the bit set's brand does not need to match the driver or its battery platform. This is different from batteries, where each maker's pack fits only its own tools.

Battery labels confuse many buyers comparing sets that are sold alongside tools. DeWalt's 20V MAX packs have a nominal voltage of 18 V, the same nominal figure as Milwaukee M18, Makita 18V LXT and Bosch 18V tools; the higher number is the maximum initial voltage without load. Our guide to 18V and 20V MAX battery naming explains which batteries fit which tools. None of that affects the bits: a SHOCKWAVE set works in a DeWalt driver, and a FlexTorq set works in a Makita one.

The one fit check that does matter is the holder. Bit holders for insert bits are made to the DIN ISO 1173-D 6.3 form, per Wera, and power bits carry a groove for the driver's ball-detent chuck. Milwaukee, DeWalt and Makita list a bit holder in their sets; Bosch's contents list does not name one, so plan on a holder if you do not already own one. To see the published chuck size for your driver, use the accessory finder.

04How do the four impact bit sets differ?

The sets differ by which drive types they include and by what comes alongside the bits, more than by the bits themselves. All four are impact-rated with a torsion design, so the choice rests on contents.

Milwaukee vs DeWalt: hex bits or sockets?

Milwaukee's SHOCKWAVE set adds hex bits to the usual Phillips, square, slotted and Torx, plus a magnetic holder and nut drivers. DeWalt's FlexTorq set swaps hex bits for sockets, a socket adaptor and a screw-lock sleeve, and supplies its bits in short and longer lengths. If you assemble furniture or machinery with hex socket screws, the Milwaukee contents fit better; if you tighten small nuts and bolts, the DeWalt sockets do.

Makita vs Bosch: spares or spread?

Makita's Impact XPS set is weighted towards insert bits, with fewer power bits, two nutsetters and a socket adapter. That suits work where one drive does most of the driving and bits wear out in turn. Bosch's Impact Tough set spreads its insert bits across Phillips, square and Torx sizes and adds a long double-ended bit. It suits a user who meets many screw sizes in small numbers.

Which set suits Pozidriv screws?

None of the four makers lists Pozidriv bits in these sets. That matters to anyone whose screws use Pozidriv recesses, in the US or in Europe. A Phillips bit only loosely fits a Pozidriv screw and cams out under torque, and a PZ bit fits a Phillips screw poorly and is likely to slip. If your screws carry the extra tick marks of Pozidriv, add PZ bits to whichever set you choose.

05When is an impact bit set the wrong buy?

An impact bit set is the wrong buy when your screws use drives the set does not include, when you need precision or specialty drives, or when you are really after drill bits. Rating and brand do not fix a mismatch of drive type.

• Mostly Pozidriv screws. As above, none of these four sets lists PZ bits.
• Drilling holes. A driver bit set does not drill. Impact-rated twist drill bits also use the 1/4 in hex, but they are a separate purchase; our hub of drill bits by material groups the options.
• Only a drill/driver, no impact driver. Impact-rated bits work in drill/drivers and hand holders too, but they give little advantage there. A standard set may serve if you never use an impact driver.
• Specialty fasteners. Security, tri-wing and other specialty drives are not part of these sets.

Two beliefs about bits are worth correcting. The first is that impact-rated bits only work in impact drivers; they also work in drill/drivers. The second is that Phillips screws were designed to cam out on purpose to stop overtightening. That idea is widespread, but there is no good evidence for it and the original patents do not mention it. Cam-out is the driver slipping out of the recess once torque passes a limit, and the cure is the right bit size and drive, held straight under steady pressure.

06How do you make impact bits last longer?

Use the correct drive and size for each screw, keep the bit in line with the screw, and replace a bit as soon as its tip rounds. Most early failures come from a poor fit between bit and recess rather than from the bit itself.

• Match bit size to recess. Use the bit size marked for the screw; a bit that sits loose in the recess slips out under torque and rounds both the bit and the screw head.
• Use Torx or square where you can. Those drives are regarded as resisting cam-out better than Phillips, which reduces tip wear.
• Keep the driver in line with the screw. A bit that enters the recess at an angle does not seat fully, which invites cam-out.
• Use a power bit for reach. Power bits lock straight into the driver's chuck for screws set in recesses.
• Retire worn bits. A rounded tip cams out more often and damages screw heads.

If you are building out a kit of starter accessories, our guide to router bit sets for beginners applies the same contents-first approach to a different tool, and the accessory buying guides section lists every comparison on the site.

07Questions readers ask