What a Drill Bit Is and How It Is Built
A drill bit is a cutting tool that removes material to make a round hole. Most bits share a few features, and knowing them makes the differences between types easier to follow.
- Point or tip: the part that starts the cut. It may be a simple angled point, a centering spur, or a carbide wedge.
- Cutting lips: the edges that actually shear or crush material.
- Flutes: the spiral grooves that carry chips and dust out of the hole.
- Shank: the end that sits in the drill. Round, hex and SDS shanks are all common. See our guide to drill shank and chuck types for the details.
Bits are usually grouped two ways: by the material they are designed to cut, and by the shape of the tip and flutes.
The Main Types of Drill Bits
If you only want a short answer to “what are the main types of drill bits”, most general-purpose guides name three groups: twist bits (for metal, plastic and general use), brad point or other wood bits, and masonry bits. Beyond those, a number of specialised bits cover particular jobs.
Twist Drill Bits
The twist bit is the standard, general-purpose bit. It has a spiral flute and an angled point, and it is commonly made from high-speed steel (HSS). It can drill wood, plastic and many metals, though it is not the best choice for fine woodworking because the point can wander and the exit hole can splinter.
If your twist bits have gone dull, a hand-sharpening guide can help you decide whether a bit is worth saving.
Brad Point Bits
A brad point bit is a twist-style bit with a small central spike and sharp outer spurs. The spike keeps the bit from wandering at the start, and the spurs score the wood fibres, which usually gives a cleaner hole. They are popular for cabinetry and furniture work. More woodworking options are covered in types of wood drill bits.
Spade (Paddle) Bits
Spade bits are flat, with a centre point. They cut larger holes quickly in wood, such as for running cable through studs. The cut is rougher than a brad point or Forstner bit, so they suit rough carpentry more than visible work.
Auger Bits
Auger bits have a deep spiral and often a threaded screw tip that pulls the bit into the wood. They clear chips well, so they are used for deep holes in timber and for boring through beams.
Forstner Bits
Forstner bits cut flat-bottomed holes with clean edges. They are often used for hinge cups, shallow recesses and overlapping holes. They are generally used in a drill press, although they can be used in a hand drill with care.
Masonry Bits
Masonry bits have a hardened tip, usually carbide, that crushes and grinds brick, block, concrete and stone rather than slicing it. They are typically used with a hammer drill setting. For heavy work in concrete, SDS bits designed for rotary hammers are the usual choice; see types of SDS drill bits.
Step Bits
A step bit is a cone with several stepped diameters. It drills thin sheet material, such as sheet metal or plastic, and one bit can make several hole sizes. It also tends to leave a cleaner, deburred hole in thin stock.
Glass and Tile Bits
These have a spear-shaped carbide or diamond-style tip designed for brittle, hard surfaces. Most manufacturers recommend low speed, light pressure and keeping the bit cool. Check the instructions on the specific bit, because some are not meant for hammer mode.
Countersink and Other Specialty Bits
Countersink bits cut a conical recess so a screw head sits flush. Installer (or bell hanger) bits have a hole through the tip for pulling cable. Multi-purpose bits are designed to handle several materials, but they are usually a compromise compared with a dedicated bit.
Hole Saws
Strictly speaking, hole saws are not bits, but they are used in drills to cut large round holes. They are covered in types of hole saws.
Drill Bit Materials and Coatings
Material matters about as much as shape.
- High-speed steel (HSS): a common, affordable material for general drilling.
- Cobalt (HSS-Co): an HSS alloy often chosen for harder metals such as stainless steel.
- Carbide-tipped: used for masonry and sometimes for hard or abrasive materials.
- Coatings such as black oxide or titanium nitride: these are generally promoted as reducing friction and wear, though results depend on the bit and use.
How to Choose the Right Drill Bit
- Start with the material. Wood, metal, masonry and glass each call for a different bit type.
- Think about the hole. Is it a clean hole in visible work, a rough hole through framing, a flat-bottomed recess, or a large opening?
- Check the drill. Make sure the shank fits your chuck. Hex and SDS shanks need compatible tools.
- Match speed to the bit. Larger bits and harder materials usually call for slower speeds. Follow the maker’s guidance.
- Consider the machine. Precise or large holes are often easier on a drill press; see types of drill presses.
Frequently Asked Questions
What are the three main types of drill bits?
Different sources group them slightly differently, but twist bits, wood bits (such as brad point) and masonry bits are the most common three.
Can I use one bit for every material?
Multi-purpose bits exist, but for good results and bit life it is usually better to use a bit designed for the material.
What are the five types of drills?
That question refers to the drills rather than the bits. Common examples include corded and cordless drill/drivers, hammer drills, rotary hammers (SDS) and drill presses. Names and groupings vary by source.
Are router bits the same as drill bits?
No. Router bits are designed for side cutting with a router, although CNC machines also use end mills that can plunge. See router and CNC router bit types.