Drill bits by material: HSS, cobalt, carbide and coatings

Last updated 2026-09-30

The best drill bit depends on what you're drilling and how many holes you need.

High-speed steel (HSS): the general-purpose choice for wood, plastic, aluminum and mild steel.
Cobalt (M35, about 5% cobalt; M42, about 8%): holds its hardness at high heat, for stainless steel, hard alloys and tough metals. Cobalt is harder but more brittle than HSS, so keep the drill steady.
Solid carbide: very hard and wear resistant, for production drilling in rigid machines; brittle in hand drills.
Carbide-tipped masonry: for concrete, brick and block, usually with a hammer drill. SDS bits fit SDS rotary hammers.

Black oxide: reduces friction and adds mild rust resistance; a good everyday HSS finish.
Titanium nitride (TiN, gold color): a hard surface coating that extends life in production work. Once sharpened, the coating is gone from the cutting edge.

118°: the common general-purpose point for softer materials.
135° split point: starts without walking and cuts harder metals better; good when you can't center-punch.

Jobber length: the standard all-round bit.
Screw machine (stubby): short and stiff, more accurate and less likely to break.
Taper length / aircraft extension: for deep holes or reaching past obstacles.

Use cutting fluid, run slower speeds for larger bits and harder materials, and use steady pressure. See cutting fluids.