Driver Bits

A driver bit drives screws. A drill bit drills holes. The key to remembering the terms is to attach the appropriate verbs: a driver bit drives screws, while a drill bit drills holes. Get that straight and the rest of the buying decision falls into place.

Here’s the short version for anyone standing at the counter. Driver bits apply torque to screws — they are the interface that transfers torque from a tool, such as a screwdriver, t-handle, or drill, to the mating recess on top of a helically-threaded fastener. Made from hardened steel to withstand high torque, driver bits are often used with bit holders for better control, and they generally have hex shanks. The vast majority use a ¼-inch hex shank (equivalent to 6.3 mm), standardized for compatibility across hand tools, drills, and impact drivers.

Two decisions matter more than anything else. Match the bit type and size exactly to the screw head. And if you’re running an impact driver — which most crews are — buy impact-rated bits. Everything past that is detail.

Drive Types and Sizing

The wrong drive type or the wrong size is the number one reason screws strip and bits skate out of the head. It’s always important to match the driver bit exactly to whatever screws you’re purchasing. The good news: the size of the tip on each driver bit is engraved on the base of the driver bit — it’s pretty faint and requires good light and maybe some reading glasses to see.

Here are the drives a building-supply customer actually runs into.

Phillips is the workhorse. They come in #1, #2, and #3 sizes, and Phillips #2 is probably the most common size. Worth knowing how Phillips behaves under load: it cams out once the screw is installed to prevent overtorqueing and damage to the substrate. That cam-out is by design, not a defect — but it’s also why people chew up heads when they push too hard.

Square (Robertson) holds tight. Square driver bits are commonly used for deck screws, though their popularity has been somewhat replaced in recent years with the Torx head screw, and they come in #1, #2, and #3. The reason carpenters like them: a tapered, square driver retains the screw on the bit until installed, it’s self-centering, the drive recess rarely strips, and it reduces product damage.

Torx (star) is the one to reach for if you’re tired of stripping. Their specific design makes it very difficult for the bit to skip within the head of the screw and strip it out. The additional bit and screw contact points increase torque transmittance, give long bit life, require minimal downward pressure to drive the screw, and produce little to no cam out. The catch is sizing — the most important component with star bits is to make sure you’re using the correct size, since they’re close enough in size that this can be tricky if you’re not paying close attention. Star bits come in the widest array of sizes from T1 all the way up to T100, but in DIY you’ll mostly work with T10, 15, 20, 25, and 30.

Slotted, Hex (Allen), and Pozidriv round out the list. Slotted shows up on flathead screws, though a hand screwdriver often makes more sense there. Hex (Allen) bits are common in machinery and furniture assembly, and Pozidriv is similar to Phillips, with 90° contact angles and additional ribs for improved grip.

Drive	Common sizes	Notes
Phillips	#1, #2, #3 (#2 standard)	Cams out under high torque by design
Square (Robertson)	#1, #2, #3	Retains screw, self-centers, rarely strips
Torx (star)	T10, T15, T20, T25, T30 (DIY range)	Most contact points, resists cam-out
Slotted	Two sizes	Flathead screws; hand driver often better
Hex (Allen)	Varies	Furniture, machinery, set screws

One mismatch to drill into your head: a #1 Phillips bit in a #2 Phillips screw will strip the screw. Read the engraving. Match the number.

Impact-Rated Bits vs. Standard Bits

This is where money gets wasted. An impact driver doesn’t work like a drill. Unlike drills, which apply continuous rotational force, impact drivers deliver intermittent bursts of high torque, and this subjects bits — especially at the tip and shank — to repeated shock loading.

Standard bits can’t take it. Standard bits typically share the same ¼″ hex shank but often fail prematurely in impact drivers — their harder heat treatment improves wear resistance but makes them more brittle, leading to chipping and fatigue cracks under repeated torque. Put plainly: non-impact driver bits should never be used in an impact driver because they’re not built to hold up against the torque.

Impact-rated bits are engineered for the shock. Manufacturers developed them specifically to withstand these stresses, and common features include torsion zones that flex to absorb torque spikes, tougher steel alloys such as S2 tool steel, and ductile heat treatment to reduce brittleness.

The flexibility runs one direction. Impact-rated bits remain backward-compatible with drills and manual screwdrivers, though their enhanced design provides no significant advantage in those contexts. So a box of impact-rated bits covers the impact driver and the drill both. The reverse does not hold.

When does the upgrade pay off? Standard bits may suffice in low- to moderate-torque tasks, but impact-rated bits offer greater durability when driving large fasteners, working in dense materials, or under sustained commercial use. Western Building Center carries impact-rated Torx, Phillips, and square bits across the common sizes — PH#2, T25, SQ#2 — in 1, 2, 3, and 6-inch lengths, along with impact set kits like the Milwaukee 32-piece impact driver set and a 100-piece impact bit set.

Specialty Bits and Accessories

A few bits solve problems the standard set won’t touch, and these matter for the kind of work that happens on Montana jobsites.

Nut drivers for metal roofing. A nut driver is one of the only driver bits that is concave instead of convex, designed for hex-cap screws. These screws, which look like a hybrid between a screw and a bolt, are common in securing metal roofing or where a structural-but-decorative screw is needed, like securing Simpson’s black brackets. Because a nut driver is designed for a screw and not a bolt, it comes in smaller sizes like 1/4″, 5/16″, and 3/8″. Anyone fastening standing seam or screw-down panel work knows these by heart.

Six-inch square (Kreg Jig) bits for pocket screws. Best known as the Kreg Jig bit, the length allows the drill to access the screw even at the sharp angle of the deep pre-drilled pockets, and because this bit isn’t unique to Kreg Jig, you can purchase your own 6-inch #2 square driver bits for replacements or back-ups.

Bolt extractors for the jobs that fight back. These are driver bits with a very specific purpose — extracting bolts — designed to remove stubborn bolts that have rusted, rounded off, or been painted over.

On accessories, a few earn their place in the pouch:

• Drive guide: a hollow tube with an internal driver bit eliminates screw wobbling during installation.
• Socket adapter: a driver bit that attaches ratchet-driven sockets to a screwdriver, t-handle, or drill.
• Drive extension: a rigid extension of tool-grade material that increases the distance between the bit and torque driver — helpful for hard-to-reach screws and bolts.
• Flexible/pivot extension: transmits torque to bolts or screws inaccessible to typical tooling, in two common styles — a long metallic hose with an internal flexible shaft, and a dual-revolute joint most effective at short distances.
• Right-angle adapter: transmits torque through bevel and miter gearing.

On material, the rule of thumb is simple. S2 tool steel offers excellent wear resistance and durability, making it a preferred material for quality-conscious users. Titanium-coated bits add wear resistance on top of that. Western Building Center stocks specialty pieces too — spider driver bits, Torx bit sockets in T40, T50, and T55, square drive socket adapters, and titanium bit sets.

Buying a Set vs. Individual Bits

For most buyers, the set wins. A set is often more economical than buying individually — it typically contains multiple tools, allowing users to purchase them once, eliminating the hassle and cost of repeated purchases. A kit keeps things sorted, too: having the right driver bits in an accessible, organized place is a real time-saver.

Buy smart, though. Don’t pay for a drawer full of tips you’ll never spin. Look for a set heavy on the sizes you actually use — PH2, T25, SQ2 — rather than padded with obscure ones. If you’re a professional or experienced DIY enthusiast performing high-intensity fastening tasks, a professional impact driver bit set provides more stable and durable tool support. The better sets bundle the helpers worth having: an impact bit holder for confined spaces, socket adapters that convert the ¼-inch hex chuck to a square drive for sockets, and impact nut setters for nuts and bolts.

Frequently Asked Questions

What’s the difference between a driver bit and a drill bit? A driver bit drives screws; a drill bit drills holes. A drill bit is used with a drill to create holes, while a driver bit, also called a screw bit, is used to fasten screws and sometimes nuts and bolts. They look different at the tip but often share the same ¼-inch hex shank, so a bit holder lets you swap between them quickly.

What size Phillips bit do most wood screws use? A #2 Phillips. Phillips #2 is probably the most common size. Driving a #2 screw with a #1 bit will likely strip the head — check the faint size engraving on the base of the bit before you start.

Can I use a regular bit in an impact driver? You shouldn’t. Non-impact driver bits should never be used in an impact driver because they’re not built to hold up against the torque. The shock loading chips and cracks standard bits. Impact-rated bits handle it — and they still work fine in a regular drill, so they cover both tools.

Which bit is least likely to strip a screw? Torx. The additional bit and screw contact points increase torque transmittance, give long bit life, and produce little to no cam out. Square (Robertson) runs a close second — square driver bits provide a secure connection and are less likely to cam out compared to Phillips.

What bit do I need for metal roofing screws? A nut driver. It’s designed for hex-cap screws, which are common in securing metal roofing, and comes in smaller sizes like 1/4″, 5/16″, and 3/8″. Match the nut driver size to the hex head on your roofing fastener.

Why does my bit keep slipping out of the screw? Usually a size or type mismatch, or too little downward pressure. Match the bit exactly to the head, keep the bit square to the fastener, and lean into it. If you’re fighting Phillips cam-out on high-torque drives, switching to Torx or square fasteners largely solves the problem.