What drill bit for metal?

Last updated: July 15, 2026

To drill metal you need an HSS (high-speed steel) twist bit at minimum, and a cobalt one for stainless or hardened steel. Not a brad-point wood bit, and not a carbide masonry bit — metal needs a bit that shears a chip, started with a centre punch and driven slow. Here's which bit to buy, why the point angle decides whether it bites or skates, and how to drill steel without burning the bit.

The short answer: to drill metal you need an HSS (high-speed steel) twist bit at minimum — and for stainless or hardened steel, a cobalt one. Not a brad-point wood bit (the centre spike is for slicing wood fibres) and not a carbide masonry bit (that chips concrete under hammer blows). Metal needs a bit that shears a chip, started with a centre punch and driven slow.

HSS at minimum — not a wood or masonry bit

A metal drill bit is a twist bit: two spiral flutes and a conical point that shears a curl of metal off as it turns. HSS (high-speed steel) is the baseline material, and a sharp HSS bit drills mild steel, aluminium, brass and plastic without complaint. A wood brad point or a masonry bit won’t do this job — the brad point’s spike and spurs are shaped to slice wood fibres, and a masonry bit’s blunt carbide wedge is made to pulverise concrete under a hammer drill, not to cut steel. (Telling the three apart is the wood vs metal vs masonry comparison.)

Which metal bit to buy: HSS, cobalt, titanium, carbide

• HSS (M2) — the baseline. Mild steel, aluminium, brass, plastic. Cheapest, and fine for most DIY. Buy a sharp set and keep it sharp.
• Cobalt (HSS-Co, M35 / M42) — the upgrade that matters. Stainless, hardened steel, and any alloy that work-hardens. The cobalt is alloyed through the whole bit, so it takes the heat and survives resharpening. This is the one to buy for stainless.
• Titanium (TiN-coated) — mostly marketing. A thin gold titanium-nitride coating on an ordinary HSS bit. It cuts a little better than bare HSS when new, but the coating is gone the moment you sharpen it — underneath it’s just HSS. A gold bit is not a cobalt bit.
• Carbide — hard and brittle. For abrasive or very hard material. It holds an edge but chips if you flex it, so it wants a rigid, low-runout setup, not a handheld drill wandering around. Not the DIY default for steel.

The useful version: HSS for mild steel and aluminium, cobalt for stainless. If a bit is sold on its gold colour rather than its steel, it's a TiN coating — pay for cobalt instead.

118° vs 135°: why the bit skates

The number on a bit — 118° or 135° — is the angle of its point, and it decides whether the bit bites or skates. 118° is the general-purpose default on cheap bits, good for wood, plastic and soft metal. 135° is flatter, and it’s usually a split point.

A 118° point has a small flat chisel edge across its centre that doesn't cut — it ploughs. On hard, flat steel that chisel skates across the surface instead of biting, which is the number-one reason a beginner's bit wanders off the mark. A 135° split point grinds that chisel down to a near-point, so it self-centres and bites where you put it. For steel, and especially stainless, a 135° split point earns its keep.

How to actually drill it

• Centre-punch first. Steel is hard and flat, so a bit walks without a divot to sit in. One tap with a centre punch (or a nail) gives the point a start — this alone fixes most skating.
• Go slow. Heat kills bits, and speed makes heat. Small bits (up to 1/8") can run around 3000 RPM; larger bits want 350–1000 RPM, and harder metal wants slower still. If the bit smokes, chatters or turns blue, you’re going too fast.
• Use cutting fluid on steel 1/8" and up. A few drops keep the edge cool and cutting; it’s not optional on anything substantial. Aluminium is happy with a little wax or WD-40; drill cast iron dry.
• Let it cut — steady, firm pressure. Enough to peel a continuous chip. Rubbing without cutting work-hardens the steel, and once the surface is glazed hard, nothing will drill it.
• Step up for big holes. Drill a smaller pilot first, then open it out — a large bit’s chisel edge struggles to start on its own. Deburr the hole afterwards with a larger bit or a countersink.
• Wear eye protection. Metal swarf is sharp, hot and comes off fast.

So which do you need?

• Mild steel, aluminium, general work: a sharp HSS twist bit, centre-punched, driven slow.
• Stainless or hardened steel: a cobalt bit with a 135° split point, cutting fluid, slower still.
• Fastening into metal? That’s a screw question, not a bit question — size a pilot for a self-tapping screw, or check whether a self-drilling (TEK) screw will get through your steel.
• Comparing wood, metal and masonry bits? The bit-type comparison guide tells them apart at a glance.
• Need a specific size? The size converter, the size chart and the number & letter chart cover the systems.