Drilling wood is different from drilling metal, and using the right bit type makes a huge difference. The hole quality, the noise, the tear-out on the exit side, and the speed all vary dramatically depending on which bit you pick.
This guide breaks down the main wood drill bit types, when you actually need each one, and which will save you time and frustration on your next project.
Brad Point vs Twist vs Spade — Quick Comparison
astic, copper.
Speeds: 1000–3000 RPM depending on material hardness. Slower for harder steel, faster for soft metals and plastic.
Cost: Budget-friendly, typically £0.20–£1.50 per bit.
Durability: Wears quickly in stainless steel and hardened steel. Prone to dulling if you use high speeds.
Pro tip: Use cutting oil when drilling steel—it prolongs bit life and gives cleaner holes. Without oil, HSS will blunt rapidly.
Cobalt (HSS-Co, typically 5–8% cobalt)
Best for: Stainless steel, hardened steel, cast iron, high-temperature alloys.
Speeds: 600–1500 RPM (slower than HSS, but tolerates harder materials).
Cost: £1–£4 per bit. 2–3x more expensive than HSS, but lasts 5–10x longer in stainless.
Durability: Exceptional. Cobalt stays sharp even in tough materials.
Pro tip: Always use cobalt for stainless steel. Regular HSS will overheat and seize in the hole. Cutting oil is essential.
Masonry / TCT (Tungsten Carbide Tip)
Best for: Brick, concrete, cinder block, stone (handheld drill with round shank or hammer drill with SDS).
Speed: 400–800 RPM for hand-held, higher for rotary hammers. Never run at high speed or you’ll overheat the carbide.
Cost: £0.80–£3 per bit (round shank), £2–£8 per SDS Plus bit.
Durability: Excellent in masonry. The TCT tip stays sharp through thousands of holes. Useless in metal (carbide is brittle).
Pro tip: Always use hammer/percussion mode with a hammer drill. Regular rotation alone won’t work well—the hammer action is what breaks the aggregate.
Diamond-Tipped (for tiles and stone)
Best for: Porcelain tiles, granite, marble, hard natural stone.
Speed: 400–600 RPM. Lower speeds prevent cracking and overheating.
Cost: £2–£8 per bit. Premium pricing due to diamond tips.
Durability: Extremely durable. A single diamond bit can drill 50–200 holes depending on porcelain hardness.
Pro tip: No hammer action. Mask the tile with masking tape to prevent the bit from wandering. Use water cooling for porcelain (wet it as you drill).
Brad Point (for timber)
Best for: Timber, plywood, MDF, softwood, chipboard. Not for concrete or stone.
Speed: 1000–3000 RPM. Faster speeds give cleaner entries.
Cost: £0.50–£2 per bit.
Design: Centre point (brad) for precise entry + two cutting flutes that cut outward. This prevents tear-out on entry and exit.
Pro tip: Brad points excel at clean, splinter-free holes. They’re the go-to for furniture and cabinetry.
Forstner (for large timber holes)
Best for: Large, clean-sided holes in timber (drilling for handles, dowels, hinge cups, cable runs).
Speed: 400–1000 RPM. Use low-medium speeds or the bit will chatter.
Cost: £2–£10 per bit depending on size.
Design: Circular cutting rim with a centre point. Produces a flat-bottomed hole with almost no tear-out.
Pro tip: Drill from both sides (top and bottom of timber) to avoid break-through splinter. Back-drill or use a waste board underneath.
Spade Bit (for large timber holes, budget option)
Best for: Large holes in timber (cable runs, drain holes, rough work). Not for finish work.
Speed: 600–1500 RPM.
Cost: £0.50–£2 per bit. Very cheap.
Design: Flat, paddle-shaped blade with cutting edges at the front.
Pro tip: Spade bits vibrate and cause tear-out. Use Forstner if you want clean holes. Spade bits are fine for rough work (cable/drain holes) where appearance doesn’t matter.
Drill Bit Size Quick Reference
Most common sizes for general work:
| Job | Metric Size (mm) | Imperial Size | Common Uses |
|---|---|---|---|
| Pilot holes for screws | 2–3mm | 3/32″, 1/8″ | Prevents splitting in timber |
| Wall plugs (small) | 5–6mm | 3/16″, 1/4″ | Most common for brick/plasterboard |
| Wall plugs (medium) | 8–10mm | 5/16″, 3/8″ | Heavier fixings, shelves |
| Masonry anchors (large) | 12–14mm | 1/2″, 9/16″ | Heavy wall-mounted items |
| Cable/drain holes | 16–20mm | 5/8″–3/4″ | Use hole saw or large spade bit |
| Large holes (furniture, cabinetry) | 25–50mm | 1″–2″ | Forstner bit or hole saw |
Wall Plug Sizing Cross-Reference
Confused about which drill bit matches which wall plug? Here’s the answer:
| Wall Plug Type | Drill Bit Size | Max Load (kg) | Best For |
|---|---|---|---|
| Nylon plug (red, 5mm) | 5mm masonry bit | 8–12kg | Light shelves, picture frames, light fittings |
| Nylon plug (grey, 6mm) | 6mm masonry bit | 12–18kg | Standard fixings, kitchen units |
| Nylon plug (brown, 8mm) | 8mm masonry bit | 18–25kg | Heavy shelves, radiators, towel rails |
| Nylon plug (blue, 10mm) | 10mm masonry bit | 25–40kg | Very heavy items, TV brackets on brick |
Golden rule: Drill bit size = wall plug size. A 5mm plug goes in a 5mm hole drilled with a 5mm bit. Don’t upsize the hole or the plug won’t grip.
Common Drill Bit Compatibility Mistakes
Mistake 1: Using a Round-Shank Masonry Bit in an SDS Plus Drill
Won’t fit. SDS Plus chucks accept only SDS Plus shanks. A round shank won’t engage the locking slots.
Solution: Buy an SDS Plus masonry bit set for your SDS drill. They’re not expensive and deliver much better results.
Mistake 2: Using Hammer Mode on Tiles
You’ll smash the tile to pieces. Hammer/percussion mode is for masonry only (brick, concrete). Tiles require static rotation with a diamond-tipped bit.
Solution: Turn OFF hammer mode. Use a standard drill with a tile bit and low speed (400–600 RPM).
Mistake 3: Using Regular HSS Bits for Stainless Steel
HSS will overheat, seize, and snap. Stainless work-hardens rapidly—you need cobalt.
Solution: Buy cobalt bits (M35 or M42 grade). Use cutting oil and go slow.
Mistake 4: Running Masonry Bits at High Speed
The tungsten carbide tip overheats and the tip separates from the steel shank. You’ve now wasted the bit.
Solution: Run masonry bits at 400–800 RPM. Let the hammer action do the work, not raw speed.
Mistake 5: No Cutting Oil When Drilling Steel
Friction heat dulls HSS rapidly. You’ll blunt a new bit in a dozen holes.
Solution: Use cutting oil, cutting paste, or even tap water (in a pinch). It cools the bit and extends life by 5–10x.
Mistake 6: Confusing Hex Bits with Hex Shank Drill Bits
Your drill-driver came with a hex chuck. Most people assume they can drill with it. In reality, hex bits are almost always screwdriver or impact bits, not drills. You need a chuck adapter to use round-shank drill bits.
Solution: Get a 1/4″ to 3-jaw chuck adapter (costs £3–£8) if you want to drill with a hex-chuck tool. Or use the tool for driving only.
Watch: Video Guide
Frequently Asked Questions
Can I use a round-shank drill bit in my SDS Plus drill?
No. SDS Plus chucks have two parallel slots that lock the keyed shank. A smooth round shank won’t engage and will just spin uselessly. You must buy SDS Plus masonry bits for an SDS drill.
What’s the difference between a masonry bit and an HSS bit?
Masonry bits have a tungsten carbide tip designed for concrete and brick. They’re useless in metal—the tip is brittle and will shatter. HSS is for metal and softer materials. Never use them interchangeably.
Can I drill stainless steel with regular bits?
Not well. Regular HSS bits will overheat and seize. You need cobalt (5%+ cobalt content). It costs more but drills stainless easily.
My hammer drill keeps slipping. Why?
You’re likely using a round-shank bit in high torque. The chuck isn’t holding it properly. Solution: Tighten the chuck harder, or upgrade to an SDS Plus drill + SDS Plus bits for professional reliability.
Why did my tile bit crack?
You used hammer mode. Tiles are brittle and will split under percussion. Tile bits must be used with the hammer mode OFF, at low speed (400–600 RPM), static rotation only.
How do I know what size drill bit to buy for my wall plug?
Simple: the wall plug size IS the drill bit size. A 5mm wall plug needs a 5mm hole drilled with a 5mm masonry bit. Check the plug packaging—it always says the size.
More Drill Bit Guides
Once you’ve understood shank types and materials, explore these guides for your specific job:
- What drill bit for brick and masonry
- What drill bit for concrete
- What drill bit for ceramic and porcelain tiles
- What drill bit for metal and steel
- What drill bit for stainless steel
>10mm masonry bit
Golden rule: Drill bit size = wall plug size. A 5mm plug goes in a 5mm hole drilled with a 5mm bit. Don’t upsize the hole or the plug won’t grip.
Common Drill Bit Compatibility Mistakes
Mistake 1: Using a Round-Shank Masonry Bit in an SDS Plus Drill
Won’t fit. SDS Plus chucks accept only SDS Plus shanks. A round shank won’t engage the locking slots.
Solution: Buy an SDS Plus masonry bit set for your SDS drill. They’re not expensive and deliver much better results.
Mistake 2: Using Hammer Mode on Tiles
You’ll smash the tile to pieces. Hammer/percussion mode is for masonry only (brick, concrete). Tiles require static rotation with a diamond-tipped bit.
Solution: Turn OFF hammer mode. Use a standard drill with a tile bit and low speed (400–600 RPM).
Mistake 3: Using Regular HSS Bits for Stainless Steel
HSS will overheat, seize, and snap. Stainless work-hardens rapidly—you need cobalt.
Solution: Buy cobalt bits (M35 or M42 grade). Use cutting oil and go slow.
Mistake 4: Running Masonry Bits at High Speed
The tungsten carbide tip overheats and the tip separates from the steel shank. You’ve now wasted the bit.
Solution: Run masonry bits at 400–800 RPM. Let the hammer action do the work, not raw speed.
Mistake 5: No Cutting Oil When Drilling Steel
Friction heat dulls HSS rapidly. You’ll blunt a new bit in a dozen holes.
Solution: Use cutting oil, cutting paste, or even tap water (in a pinch). It cools the bit and extends life by 5–10x.
Mistake 6: Confusing Hex Bits with Hex Shank Drill Bits
Your drill-driver came with a hex chuck. Most people assume they can drill with it. In reality, hex bits are almost always screwdriver or impact bits, not drills. You need a chuck adapter to use round-shank drill bits.
Solution: Get a 1/4″ to 3-jaw chuck adapter (costs £3–£8) if you want to drill with a hex-chuck tool. Or use the tool for driving only.
Frequently Asked Questions
Can I use a round-shank drill bit in my SDS Plus drill?
No. SDS Plus chucks have two parallel slots that lock the keyed shank. A smooth round shank won’t engage and will just spin uselessly. You must buy SDS Plus masonry bits for an SDS drill.
What’s the difference between a masonry bit and an HSS bit?
Masonry bits have a tungsten carbide tip designed for concrete and brick. They’re useless in metal—the tip is brittle and will shatter. HSS is for metal and softer materials. Never use them interchangeably.
Can I drill stainless steel with regular bits?
Not well. Regular HSS bits will overheat and seize. You need cobalt (5%+ cobalt content). It costs more but drills stainless easily.
My hammer drill keeps slipping. Why?
You’re likely using a round-shank bit in high torque. The chuck isn’t holding it properly. Solution: Tighten the chuck harder, or upgrade to an SDS Plus drill + SDS Plus bits for professional reliability.
Why did my tile bit crack?
You used hammer mode. Tiles are brittle and will split under percussion. Tile bits must be used with the hammer mode OFF, at low speed (400–600 RPM), static rotation only.
How do I know what size drill bit to buy for my wall plug?
Simple: the wall plug size IS the drill bit size. A 5mm wall plug needs a 5mm hole drilled with a 5mm masonry bit. Check the plug packaging—it always says the size.
More Drill Bit Guides
Once you’ve understood shank types and materials, explore these guides for your specific job:
- What drill bit for brick and masonry
- What drill bit for concrete
- What drill bit for ceramic and porcelain tiles
- What drill bit for metal and steel
- What drill bit for stainless steel
nd static rotation with a diamond-tipped or carbide spear-point bit.”
}
},
{
“@type”: “Question”,
“name”: “What drill bit size matches my wall plug?”,
“acceptedAnswer”: {
“@type”: “Answer”,
“text”: “The wall plug size is the drill bit size. A 5mm wall plug needs a 5mm hole drilled with a 5mm masonry bit. Check the plug packaging—it always states the size required.”
}
},
{
“@type”: “Question”,
“name”: “Can I drill stainless steel with regular HSS bits?”,
“acceptedAnswer”: {
“@type”: “Answer”,
“text”: “Not well. HSS will overheat and seize in stainless steel. You need cobalt bits (M35 or M42 grade). Always use cutting oil and keep speeds low (600–1500 RPM) when drilling stainless.”
}
}
]
}
