Drill Bit Types Explained: When to Use Each One

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A drill is only as useful as the bit in the chuck. The wrong bit for the material wastes time, damages the workpiece, and dulls the bit prematurely. Twist bits, spade bits, Forstner bits, hole saws, masonry bits, and step bits all exist because they each solve a different problem. This guide covers what each type does, what materials it works in, and when to reach for it instead of the others.

Twist Bits: The Default

Twist bits are the standard bits that come in every drill bit set. Two helical flutes spiral around a cylindrical body, cutting on the tip and clearing chips up the flutes. They work in wood, plastic, soft metal, and, with HSS (high-speed steel) or cobalt versions, in harder metals. Sizes run from 1/16-inch to 1/2-inch in standard sets. Beyond 1/2-inch, you need a reduced-shank bit that steps down to a 3/8-inch or 1/2-inch shank to fit a standard drill chuck.

For wood, twist bits are fine for small holes up to about 3/8-inch. Larger holes in wood are better handled by spade bits or Forstner bits, because twist bits tend to wander and the entry hole can splinter. For metal, standard HSS twist bits handle mild steel and aluminum well. Cobalt bits (typically a 5% cobalt alloy, labeled M35) are the right choice for stainless steel and hardened fasteners, where regular HSS dulls quickly.

A 29-piece HSS twist bit set covering 1/16-inch through 1/2-inch in 1/64-inch increments runs $15 to $40 depending on brand. DeWalt, Milwaukee, and Bosch all make reliable sets. Cobalt sets cost roughly double. For occasional home use, HSS is enough. If you drill stainless, hardened bolts, or cast iron regularly, cobalt pays for itself in bit life.

Spade Bits: Fast and Rough

A spade bit is a flat blade with a center point, sized from 3/8-inch to 1-1/2-inch. Spade bits bore through wood fast. They throw big chips, leave a rough hole, and are cheap enough to be essentially disposable. Electricians and plumbers use them heavily to drill through studs and joists for wire and pipe runs. A 3/4-inch spade bit puts a Romex-sized hole through a 2x4 in about two seconds.

Do not use spade bits for visible work. The entry and exit holes splinter, and the hole walls are rough. For clean holes in cabinet sides, furniture, or finish trim, use a Forstner bit instead. A set of six spade bits (3/8-inch through 1-inch) costs $8 to $15. They are the cheapest boring option per hole.

Keeping spade bits sharp makes a noticeable difference. Touch up the two cutting edges and the center point with a flat mill file. Five minutes of filing restores a dull spade bit to near-new cutting performance. Once the center point is too worn down to track properly, replace the bit.

Forstner Bits: Clean and Flat-Bottomed

Forstner bits cut flat-bottomed, clean-edged holes from 1/4-inch to 2-1/8-inch. A center spur guides the bit while a rim cutter scores the wood fibers before the body removes the material. The result is a hole with no splintering and a flat bottom, something twist bits and spade bits simply cannot produce. Forstner bits are slower than spade bits and work best in a drill press at 500 to 1,000 RPM.

Standard uses include 35mm hinge cups for European cabinet hinges (the most common Forstner bit application in home shops), counterbores for bolt heads and washers, overlapping holes for rough mortises, and any decorative or structural hole in visible work. Because the rim cutter does the guiding rather than the center point alone, Forstner bits can also cut overlapping holes without the center drifting into the adjacent hole. This makes them essential for cutting rectangular mortises by boring a row of overlapping holes and cleaning up with a chisel.

Individual Forstner bits cost $8 to $20 depending on size. A 16-piece set covering common sizes runs $40 to $80. For the home shop that only needs one, a 35mm bit for European hinges (about $10) is the single most useful size to own. If you are building cabinets or installing concealed hinges, this bit pays for itself on the first door.

Hole Saws: Big Circles

A hole saw is a cylindrical blade mounted on a mandrel with a pilot twist bit in the center. Hole saws cut circles from 3/4-inch to 6 inches in wood, plastic, drywall, and thin metal. The pilot bit keeps the saw centered while the teeth cut the perimeter. Bi-metal hole saws (HSS teeth on a spring steel body) handle both wood and metal. Carbide-grit saws handle tile and cement board.

Common residential uses: 2-1/8-inch for door locksets, 4-inch and 6-inch for recessed lighting, various sizes for plumbing penetrations, and standard sizes for junction box openings in drywall. Run hole saws slowly, 300 to 800 RPM depending on diameter, and back out frequently to clear chips. Forcing a hole saw generates excessive heat that work-hardens the material and strips the teeth.

A door lock installation kit (which includes the 2-1/8-inch and 1-inch hole saws, a mandrel, and a centering jig) costs $15 to $25 and is a worthwhile purchase if you are replacing door hardware. For other sizes, individual bi-metal hole saws run $8 to $20 each. Sets of 10 to 15 common sizes cost $30 to $60. Lennox, Milwaukee, and Diablo all make reliable bi-metal sets.

Masonry Bits: Concrete and Brick

Masonry bits have a carbide tip brazed onto a steel body. The tip is slightly wider than the body so the flutes clear the hole without binding. They are designed to work with the hammer function on a hammer drill, where the pulsing action pulverizes the masonry while the rotation clears debris. Sizes range from 3/16-inch (the right size for Tapcon concrete screws) to 1/2-inch (for wedge anchors and sleeve anchors).

For holes larger than 1/2-inch or in reinforced concrete with rebar, switch to a rotary hammer with SDS-Plus bits. A standard hammer drill with masonry bits tops out at about 1/2-inch diameter before the tool simply cannot deliver enough impact energy to make progress. A rotary hammer with a 3/4-inch SDS-Plus bit drills through a concrete foundation wall in seconds where a hammer drill would stall.

Masonry bits are inexpensive. A 7-piece set covering 3/16-inch through 1/2-inch runs $8 to $15. Buy carbide-tipped bits from Bosch, DeWalt, or Diablo. Avoid unbranded bits from bargain bins; the carbide tips on cheap masonry bits dislodge after a few holes in hard concrete.

Step Bits: Sheet Metal and Thin Stock

A step bit is a conical bit with stepped diameters increasing from tip to base, usually covering 1/8-inch to 7/8-inch or wider in a single bit. Each step is labeled with its diameter. Step bits cut clean, round holes in sheet metal, electrical panels, ductwork, and thin plastic. They cannot bore deep holes because the cone widens as it advances. Maximum material thickness is about 1/8-inch per step.

Step bits self-deburr as they cut, leaving a clean hole with no sharp edges. This eliminates the separate deburring step that twist bits require in sheet metal. They are the fastest way to drill multiple sizes of hole in sheet metal without changing bits: just drill to the step that matches the diameter you need and stop.

A three-piece step bit set covering 1/8-inch to 1-3/8-inch costs $15 to $30. Titanium-coated versions last longer in steel but cost more. For occasional home use (drilling through an electrical panel knockout or adding a hole to a junction box), a single step bit in the 1/8-inch to 3/4-inch range handles most tasks. Keep them sharp with a diamond file on the step edges; once the steps are rounded over, the bit tears instead of cutting.

Matching the Bit to the Job

Picking the right bit comes down to three questions: what material are you drilling, how large is the hole, and does the finish matter?

Wood, small hole (under 3/8-inch): twist bit.
Wood, large hole, rough work: spade bit. Fast, cheap, disposable.
Wood, large hole, clean finish: Forstner bit. Flat bottom, no splintering.
Wood or drywall, very large circle: hole saw on a mandrel.
Concrete, brick, block: masonry bit in hammer drill mode.
Concrete, large diameter or rebar: SDS-Plus bit in a rotary hammer.
Sheet metal, thin stock: step bit for clean, deburred holes.
Metal, general: HSS twist bit (mild steel) or cobalt twist bit (stainless, hardened).
Tile, cement board: carbide-grit hole saw or diamond-tipped bit.

Keeping a basic set of each type on hand means you never have to make a hardware store trip mid-project to get the right bit. A starter collection, covering all the types above, costs $60 to $100 total and handles virtually any drilling task a homeowner encounters.

Frequently Asked Questions

What drill bits should a homeowner have?

A basic twist bit set (1/16-inch to 1/2-inch in 1/64-inch increments), a set of spade bits (3/8-inch to 1-inch), a 35mm Forstner bit for cabinet hinges, and a few masonry bits (3/16-inch, 1/4-inch, 5/16-inch) for concrete anchors. That covers about 95% of household drilling tasks.

Why do my drill bits keep breaking?

Usually too much pressure, wrong speed, or wrong bit for the material. Metal needs slow speed and steady pressure with HSS or cobalt bits. Wood needs moderate speed. Masonry needs hammer mode. Also check that the bit is seated straight in the chuck with no wobble. A crooked bit bends under load and snaps.

Can I sharpen drill bits?

Twist bits up to 1/2-inch can be sharpened on a bench grinder or a dedicated bit sharpener. Maintaining the correct point angle (118 degrees for general purpose, 135 degrees for metal) is the difficult part. A drill bit sharpener jig holds the angle for you and costs $25 to $50. Spade bits can be touched up with a flat file. Forstner and masonry bits are harder to sharpen properly and are usually replaced when they dull.