The drill gets the glory, but the bit does the cutting — and bit choice matters more than drill choice for hole quality. A premium drill spinning a dull, wrong-type bit drills a worse hole than a basic drill with the right sharp bit. Yet most beginners buy bits the way they buy drills: by staring at a wall of options and guessing.
This guide maps the common bit families to their jobs, explains what the markings mean, and shows you how to build a bit collection that covers real projects without the 200-piece kit full of sizes you’ll never touch.
Twist bits: the everyday workhorse
The twist bit — the classic spiral-fluted cylinder — is the default bit for a reason: it drills round holes in wood, plastic, and metal competently. The flutes do double duty, cutting and evacuating chips up and out of the hole. Standard twist bits are usually high-speed steel (HSS), which handles wood, plastic, and mild steel; black oxide and titanium-nitride coatings add surface hardness and reduce friction for longer life in metal.
For metal drilling, slow down and use cutting fluid or even a drop of oil — heat is the enemy, and a smoking bit is a dulling bit. For wood, twist bits work but tend to wander on entry and leave slightly rough holes; that’s why woodworkers often prefer brad-point bits (below) for visible work. Keep a set spanning roughly 1/16 to 1/2 inch and you’ll cover the vast majority of everyday holes.
Brad-point bits: clean holes in wood
A brad-point bit looks like a twist bit with a sharp center spur and two cutting spurs at the rim. That center point bites exactly where you place it — no wandering, no pilot punch needed — and the outer spurs score the wood fibers before the main cutters remove them, leaving dramatically cleaner entry holes in wood and plywood.
If you build furniture, drill shelf-pin holes, or do any work where hole appearance matters, brad-points are worth owning. They cut aggressively, so ease off pressure as you break through the back face (or clamp a sacrificial board behind the workpiece) to avoid blowout. They’re a wood-only family — don’t use them in metal.
Spade bits: fast, rough holes in wood
Spade bits (paddle bits) are flat blades with a center point and two cutting wings. They’re the fastest way to bore holes from about 3/8 inch to 1-1/2 inches in wood — think running wires through studs or boring plumbing chases. Speed is their virtue; cleanliness is not: they leave rough holes with ragged exits.
Use them where the hole will be hidden. Run the drill at moderate speed, clear chips by withdrawing periodically on deep holes, and back the workpiece with scrap to control blowout. Spur-tipped spade bits cut cleaner than flat-ground ones and are worth the small premium if you use spade bits often.
Forstner bits: precision flat-bottomed holes
Forstner bits bore clean, flat-bottomed holes with crisp rims — the bit for concealed hinges, dowel joints, and any hole where the bottom or the edge will show. The rim cutters shear the wood fibers cleanly before the center cutters remove waste, producing holes no twist or spade bit can match for quality.
They demand respect: Forstner bits generate significant heat and need low speeds (especially in larger diameters), firm feed pressure, and ideally a drill press — though careful hand-drilling works for shallow holes. They’re poor at chip evacuation on deep holes, so peck (withdraw to clear chips) frequently. Buy them individually in the sizes your projects actually need rather than as an expensive set.
Hole saws: big diameters
When the hole exceeds what Forstner bits cover — doorknob bores, recessed lights, dryer vents — hole saws take over. A hole saw is a cylindrical saw that cuts a ring, with a pilot bit centering it. Bi-metal hole saws cut wood, plastic, and thin metal; carbide-toothed versions handle tile and masonry-like materials.
Technique matters more than brand: moderate speed, steady pressure, and frequent chip clearing. Deep cuts bind — withdraw often. The plug usually sticks inside the saw; most saws have ejection slots for a screwdriver. For doorknob-size holes in doors, a dedicated door-lock installation kit (saw + guides) pays for itself the first time you hang a door correctly.
Masonry bits: concrete, brick, and stone
Masonry bits have a carbide tip brazed onto a steel body and are designed to grind rather than slice. They require hammer-drill mode (or a rotary hammer for serious concrete work) — a standard drill in regular mode will barely scratch cured concrete. Match the bit to the fastener: drill the hole to the anchor manufacturer’s specified diameter and depth, blow or brush out the dust, and the anchor will hold as designed.
Go slow, let the hammer action do the work, and don’t force it — pressure without progress just overheats the carbide. For more than a few holes in concrete, a rotary hammer (SDS) is a different league of tool; a hammer drill is for occasional masonry, not production work.
Reading bit markings and sizing
Bits are marked by diameter in inches (fractional) or millimeters. A 1/4-inch bit drills a 1/4-inch hole — simple — but remember that screws need pilot holes slightly smaller than the screw’s shank (not its threads): the threads must bite into wood the shank would otherwise split. A common rule: pilot diameter roughly equals the screw’s root (inner) diameter; when in doubt, test on scrap.
Shank types matter for compatibility: straight shanks fit any chuck; 1/4-inch hex shanks fit impact drivers and quick-change chucks; SDS shanks fit rotary hammers only. Our How to Choose a Cordless Drill: The Complete Buying Framework covers chuck compatibility in detail. Buying a bit your tool can’t hold is the most avoidable mistake in this hobby.
Building a bit collection without waste
Skip the 200-piece kit. Start with: a 29-piece HSS twist set (1/16–1/2 by 64ths), a brad-point set in common sizes, spade bits in 1/2, 3/4, and 1 inch, Forstner bits in the two or three sizes your joinery needs, one bi-metal hole saw kit with mandrel, and masonry bits in 3/16, 1/4, and 5/16 inch. That covers roughly 95 percent of homeowner projects.
Store bits so you can see sizes — index cases beat jumbled pouches — and treat bits as consumables. A dull bit is not a tragedy; it’s a used-up supply. Learn to recognize the signs (smoke, squealing, wandering, burning smell in wood) and replace without sentimentality. Sharp bits are safer bits: they cut with less force, which means less slipping and fewer surprises.
Reading a bit set: what the numbers and coatings mean
Bit packaging is full of claims worth decoding. HSS (high-speed steel) is the baseline material for metal-capable twist bits. Black oxide adds corrosion resistance and lubricity — a genuine improvement for metal drilling. Titanium nitride (TiN) coating — the gold-colored bits — reduces friction and adds surface hardness, but the coating is thin: once it wears or you resharpen, you’re back to HSS underneath. Cobalt (M35/M42) bits are alloyed through, not coated — they stay hard at high heat and are the real choice for stainless steel and hardened materials.
Shank markings tell you compatibility: straight shanks for drill chucks, 1/4-inch hex for impact drivers and quick-change systems, SDS for rotary hammers. Length designations (jobber, stubby, extended) trade reach against rigidity — long bits wander more, so use the shortest bit that reaches. None of this is marketing; it’s the vocabulary that keeps you from buying the wrong bit twice.
Drilling technique: speed, pressure, and lubrication
The universal technique rule: big bits go slow, small bits go fast. A 1/2-inch bit in steel wants a few hundred RPM; a 1/16-inch bit wants thousands. Too fast on a large bit overheats and dulls it in seconds — the blue discoloration on overheated steel is the tombstone of a ruined bit. Feed pressure should be firm and steady: enough to keep cutting, never so much that the motor strains.
In metal, lubrication is transformative — a drop of cutting oil (or even household oil in a pinch) extends bit life dramatically and improves hole quality. Peck drilling (withdrawing to clear chips) prevents chip packing on deep holes. In wood, back the exit side with scrap to prevent blowout, and clear chips on deep holes so the bit doesn’t overheat and burn the wood. Technique multiplies bit life more than price does.
Storing and organizing bits so you can find them
A bit collection you can’t navigate is a collection you rebuy. Index cases — the metal or plastic boxes with labeled holes — are the standard for twist bits: every size visible, empties obvious. Forstner bits want individual sleeves or a fitted case (their rims chip if they bang together). Spade bits hang on a wall strip or live in a roll. Hole saws stack in a case with the mandrel and pilot bits.
Label anything unlabeled: a permanent marker with the size on the shank saves endless test-fitting. Keep a small “sharpen or replace” tray — dull bits go there, not back in the case, so you never grab a dead bit mid-project. And resist the 200-piece kit temptation: a curated set you understand beats a comprehensive set you can’t navigate.
Frequently asked questions
What’s the difference between HSS and titanium bits?
HSS (high-speed steel) is the base material. ‘Titanium’ bits are HSS with a titanium-nitride coating that reduces friction and adds surface hardness. The coating helps in metal but wears off with use and can’t be resharpened — underneath, it’s still HSS.
Why do my bits wander when I start a hole?
Smooth twist bits skate on hard surfaces before biting. Fix it with a center punch dimple in metal, a brad-point bit in wood, or simply starting at low speed with firm pressure. Never start a large bit at full speed on an unmarked surface.
Can I sharpen drill bits?
Twist bits can be sharpened with a bench grinder or dedicated sharpener if you maintain the correct angles — a skill worth learning for expensive bits. Cheap small bits are usually more economical to replace. Spade and Forstner bits can be touched up with a file or diamond paddle.
Do I need special bits for an impact driver?
For driving, yes — impact-rated hex-shank bits. For drilling with an impact driver, use hex-shank drill bits rated for impact use. Standard round-shank bits need a drill chuck, not an impact driver.
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