1 1/16 Drill Bit Size Chart: What Diameter and Shank Fit Your Tool?

A 1 1/16 in drill bit cuts a 1.0625 in (26.99 mm) hole, but its shank — the part that enters your chuck — is a separate spec that varies by bit type and must match your tool exactly.

Buying a bit by diameter alone is how people end up with a tool that won’t grip it. A 1 1/16 in bit is a large cutting size, and the shank bolted onto it can range from a 7/16 in hex to a 1/2 in reduced straight shank depending on what the manufacturer built it for. Miss that difference and the bit never spins.

What Diameter Does A 1 1/16 Drill Bit Actually Cut?

The cutting diameter is 1.0625 in, which converts to 26.9875 mm. That number is fixed — 1 1/16 in is 1 plus 1/16, and 1/16 in equals 0.0625 in, so the decimal form is 1.0625 in every time.

For metric tooling and collets, that’s 26.99 mm when rounded to two places. A hole drilled at this size is often a clearance hole for a 1 in bolt or a pilot for larger bore work, which is why machinists keep the conversion handy instead of guessing.

Those shank figures are the ones that trip people up. The cutting diameter is always 1.0625 in, but the shank sitting behind it is smaller — often 7/16 in or 1/2 in — so a standard 1/2 in chuck can accept a large bit it otherwise couldn’t hold.

Why Do Two 1 1/16 In Bits Have Different Shanks?

Because diameter and shank are two independent specs, and a manufacturer picks the shank to suit the tool the bit targets. A ship auger bit at 1 1/16 in is commonly sold with a 7/16 in hex shank, sized for a drill or impact driver with a hex quick-change holder.

A reduced-shank drill bit at the same 1 1/16 in diameter typically ships with a 1/2 in straight-cylindrical shank instead. Morse taper versions exist too, cut for a machine spindle rather than a hand drill.

The practical takeaway: never assume two bits with matching diameters will fit the same tool. Open the product page, find the shank spec, and match it to what your chuck or holder accepts. The McMaster-Carr drill bit size chart is a solid reference for cross-checking decimal equivalents before you buy. If you want a shortlist of bits that actually fit common 1/2 in chucks, this roundup of tested 1 1 16 drill bit picks covers the compatible options directly.

Will A Bit This Large Fit A Normal Drill?

Only if the chuck capacity covers the shank, not the cutting diameter. A 1/2 in keyed or keyless chuck accepts anything up to 1/2 in, which means 7/16 in hex and 1/2 in reduced shanks both slot in fine.

The bit’s 1 1/16 in cutting size sits entirely outside the chuck jaws, so chuck capacity has nothing to do with how wide the hole ends up. What matters is whether the shank’s own size and shape match the jaws or holder.

• Hex shank: needs a quick-change holder or a three-jaw chuck that grips hex stock; common on auger and spade bits.
• Straight-cylindrical shank: fits a standard three-jaw chuck within its rated capacity.
• Taper shank: seats in a matching machine spindle taper, not a hand-drill chuck.

Check your tool’s rated chuck capacity before buying, and confirm the exact shank geometry listed. A 1/2 in straight shank in a 3/8 in chuck simply won’t seat, no matter how much you tighten it. Grainger’s listing for a 1 1/16 in Cleveland taper shank drill bit shows how differently these large bits are configured depending on the machine they’re meant for.

Common Mistakes To Avoid

• Confusing the 1.0625 in cutting diameter with the shank diameter — they’re separate numbers.
• Assuming every 1 1/16 in bit uses the same shank style; they don’t.
• Forcing a shank larger than the chuck capacity, which damages jaws and ruins the bit’s runout.
• Skipping the tool’s load rating — a bit this size bites hard and demands a drill built for it.

Verify two specs before you buy: the bit’s shank size and your tool’s chuck capacity. Match both and the bit spins true; miss either and it’s a paperweight.