9/16 Drill Bit: Check Diameter, Shank and Material

A 9/16-inch drill bit has a nominal cutting diameter of 0.5625 inch, or exactly 14.2875 mm. That is the hole-size designation—not necessarily the diameter of the shank that your drill grips.

If you need a 9/16-inch hole, buy that cutting diameter, then choose the bit design for the material and check its shank against your chuck. A metal twist bit, wood spade bit and concrete hammer bit can all carry the same size marking without being interchangeable.

What size is 9/16 inch?

Size	Decimal inches	Millimeters
1/2 inch	0.5000	12.7000
9/16 inch	0.5625	14.2875
5/8 inch	0.6250	15.8750

These are calculated nominal conversions, not measurements of finished holes.

Neither 14 mm nor 14.5 mm is an exact replacement:

• A 14 mm bit is 0.2875 mm smaller in nominal diameter.
• A 14.5 mm bit is 0.2125 mm larger in nominal diameter.

Use a substitute only if the drawing, hardware instructions or allowable hole tolerance permits it. For a fitted part or specified anchor hole, being the nearest size is not enough. Likewise, a fastener’s diameter alone does not establish its clearance-hole or tap-drill size.

Will it fit a 1/2-inch drill chuck?

It can, if the shank fits—but not simply because it says 9/16 inch. Chuck capacity describes the largest shank it can grip, rather than every hole diameter the drill can produce. University of California’s portable-drill safety guidance explains that distinction.

For example, Milwaukee’s 48-89-4634 Silver and Deming twist bit has a 9/16-inch cutting diameter and a 1/2-inch shank. That shank fits a chuck rated to accept 1/2 inch; it does not fit a chuck limited to 3/8 inch.

A different design may have a much smaller shank. Diablo’s DSP2060 wood spade bit cuts at 9/16 inch but has a 1/4-inch hex shank.

Shank fit is only the first check. Also confirm your drill’s rated hole diameter for the intended material. For example, the Makita DS4000 manual lists a 1/2-inch capacity in steel and 1-1/2 inches in wood. A smaller shank does not increase those ratings.

Choose the cutting design for the job

Metal: a metal-rated twist bit

For a straight hole through thicker metal, look for a metal-rated twist bit with enough usable flute length. The Milwaukee example above lists steel, stainless steel, aluminum and cast iron among its material applications. Its listed dimensions are 6 inches overall with 3.15 inches of flute length—not 6 inches of drilling depth.

For thin sheet, a step bit is another option. Verify that it includes a 9/16-inch step and that the sheet fits within the manufacturer’s thickness limit. IRWIN’s Unibit #20 covers 9/16 to 1 inch, is intended for thin materials and explicitly requires a pilot hole. See our step-bit guide before choosing it for thicker stock.

Wood: a wood-boring bit

For a general through-hole in clean wood, a 9/16-inch spade bit is a practical option. Diablo rates the DSP2060 for hardwoods, softwoods and plywood. For visible joinery or a blind recess, compare other designs in our wood drill-bit guide.

Concrete: a compatible hammer bit

Choose a concrete-rated bit with the shank system your tool requires. Bosch’s HCFC2092, for example, is a 9/16-inch SDS-plus rotary-hammer bit with 4 inches of working length and 6 inches overall. Bosch specifies it for SDS-plus rotary hammers; do not treat it as a reduced-shank twist bit for an ordinary chuck.

Before drilling

Secure the work, wear eye protection and follow the bit and drill instructions. For drill-press work, use a clamp or drill vise rather than holding the piece by hand. Clear deep holes frequently and reduce pressure as the bit breaks through, as advised in CCOHS drill-press guidance. For metal, follow the tooling instructions on lubrication; not every metal calls for the same approach.

Before buying, verify four entries on the specification sheet: 9/16-inch cutting diameter, material application, shank size/type and usable drilling depth. Overall length alone does not settle the last one.