Drill bit sets are organized by material — twist bits for wood and metal, carbide masonry bits for concrete, and multi-purpose sets that try to cover everything.
Pick the wrong bit and you’ll ruin the bit — or crack a brick and strip a screw. Wood, metal, and concrete sizing run on three different numbering systems, so a 5/32 inch bit means something different depending on the material. This guide covers what each bit type handles, how US sizing works, and where sizing mistakes happen — so you buy one set that fits the work, not three.
What Each Bit Type Does (And What It Won’t)
High-speed steel (HSS) twist bits cut wood, plastic, and soft metals like aluminum and brass; most guides recommend a few drops of cutting oil on metal to keep heat down and extend bit life. On concrete, HSS dulls almost immediately and leaves a dirty hole. Carbide masonry bits cut concrete, brick, and block, pairing with a hammer drill in hammer mode — no cutting oil, since masonry dust doesn’t benefit from lubrication the way metal chips do. One widely cited masonry chart lists Tapcon 3/16 inch screws matched to a 5/32 inch carbide bit, and 1/4 inch Tapcon screws matched to a 3/16 inch carbide bit. Multi-purpose sets combine wood, metal, plastic, and light masonry bits in one case; Universal’s 40-piece set (DRA10878) and 100-piece version (DRA76594) both claim wood, metal, plastic, brick, and concrete block coverage, but their masonry bits are sized for light work, not foundation anchors.
- Wood and metal: HSS twist bits, cutting oil on metal
- Concrete and brick: Carbide masonry bits, hammer mode, no oil
- Mixed jobs: Multi-purpose sets, but check masonry bit sizes before buying
How US Drill Bit Sizing Actually Works
US drill sizes come in three families — fractional inches, number sizes, and letter sizes — each showing up in different parts of the work, so a full set usually includes more than one type. Fractional sizes run from 1/16 inch to 1/2 inch in most homeowner sets, stepping through 1/16, 5/64, 3/32, 7/64, 1/8, 9/64, 5/32, and so on, covering woodworking pilot holes, general drilling, and most wall anchors. Number sizes (like #6, #10, #12) and letter sizes (like F and I) appear mostly in tap-drill work. Bolt Depot’s US tap and drill size table lists 7/64 inch for #6-32, 5/32 inch for #10-24, 11/64 inch for #12-24, 13/64 inch for 1/4-20, and 27/64 inch for 1/2-13; letter sizes cover less common threads, including F for 5/16-18 and I for 5/16-24. Tap-drill sizes are for cutting threads — not clearance holes. Mixing the two up is a common reason a bolt won’t thread or a screw strips its hole.
Common Sizes and What They’re For
Most everyday drilling — pilot holes, anchors, general fastening — lands on a handful of sizes:
- 1/8 inch: general-purpose wood and light metal drilling
- 5/32 inch: pilot holes for #8 wood screws, and the matching bit for 3/16 inch Tapcon screws
- 3/16 inch: pilot holes for #10 wood screws, and the matching bit for 1/4 inch Tapcon screws
- 1/4 inch: general drilling, wall anchors, and light concrete work
A capable starter set covers 1/16 inch through 1/2 inch in fractional steps, plus masonry bits in the 3/16 to 1/4 inch range for household concrete and brick. For sets tested on wood, metal, and light concrete, our roundup of the best drill bit set for home use breaks down which kits hold up.
Mistakes That Ruin Bits and Holes
Nearly every drill bit problem traces back to a type or sizing mismatch — not a dull bit or weak drill. Running a wood twist bit into concrete is the number-one offender: the bit dulls in seconds, the hole comes out oversized, and the motor works harder than it should. Metric and fractional sizes are another trap — a 5 mm bit is not a 3/16 inch bit — and several manufacturers sell metric-only sets, including Makita’s 9-piece pack (D-71962) with 5, 6, and 8 mm bits for metal, wood, and masonry. If your project uses US fractional fasteners, convert before you drill. Finally, multi-purpose set claims vary: one set may cover wood, metal, plastic, brick, and concrete block, while another only includes small masonry sizes meant for drywall anchors. Check the actual bit list, not the box photo. For authoritative US sizing, use the Bolt Depot US tap and drill size table.
FAQs
Can I use a wood twist bit on concrete in a pinch?
No — HSS twist bits dull almost instantly on concrete and produce an oversized, ragged hole. Even one hole in brick or block damages the cutting edge. Use a carbide masonry bit with the drill in hammer mode.
Do I really need both fractional and number-sized bits?
For everyday drilling — pilot holes, anchors, general woodwork — fractional sizes from 1/16 inch to 1/2 inch cover almost everything. Number and letter sizes are mainly for cutting threads into metal, where tap-drill tables specify exact sizes like 7/64 inch for #6-32. Unless you’re tapping threads, fractional bits are sufficient.
Are multi-purpose drill bit sets worth buying?
They’re convenient for mixed jobs touching wood, plastic, light metal, and occasional brick. The catch is masonry depth — concrete bits in multi-purpose sets are usually small and best for anchors and light block work, not repeated drilling. For heavy concrete, buy a dedicated carbide masonry set alongside the multi-purpose kit.
References & Sources
- Bolt Depot. “US Tap and Drill Size Table.” Source for tap-drill sizing, number and letter drill sizes, and thread-matching guidance.
- Fabworks. “Drill Chart.” Reference for material-specific bit types, cutting oil use on metal, and carbide masonry guidance.
- Slugger Tool. “Drill Bit Size Chart.” Reference for fractional and metric bit size comparisons.