A 1 1/16 inch drill bit equals 1.0625 inches (26.9875 mm) and has no matching number or letter size — those series end at #1 (0.2280 in) and Z (0.4130 in).
Pull a 1 1/16 inch bit from a chart and you have a fractional tool, not a numbered one. If you’re hunting for its number or letter equivalent, none exists — it’s a large fractional bit in its own column.
Here are the exact decimal and metric values, why the number and letter series can’t get there, and what to use instead.
The Exact Decimal And Metric Size
In decimal form, 1 1/16 inch is 1.0625 in, which converts to 26.9875 mm (often rounded to 27 mm).
Fractional bits are sized by measured diameter, not a series code — unlike number and letter bits, which carry an arbitrary label tied to a diameter. A 1 1/16 inch bit’s name is its size.
So you can’t swap it for the closest number or letter size and expect the same hole; a few thousandths of an inch can mean the difference between a bolt that threads cleanly and one that wobbles.
Why No Number Or Letter Size Equals 1 1/16 Inch
The number series runs #80 to #1, and letters run A through Z — neither reaches 1 1/16 inch. The largest number size, #1, is 0.2280 in; the largest letter, Z, is 0.4130 in. Both are less than half of 1 1/16 inch.
The systems exist for small-diameter work like tapping, pilot holes, and clearance fits, and top out well before large fractional territory. Past roughly the 1/2 inch mark, most U.S. charts switch to fractional sizing. Carbide Processors’ drill bit size chart lays number, letter, and fractional sizes side by side — the fractional rows continue upward alone.
| Size System | Value At 1 1/16 Inch | Notes |
|---|---|---|
| Fractional | 1 1/16 in | The actual designation; the size is the name |
| Decimal | 1.0625 in | Exact decimal equivalent, no rounding |
| Metric | 26.9875 mm | Often rounded to 27.0 mm in informal use |
| Number series | None | Series tops out at #1 = 0.2280 in |
| Letter series | None | Series tops out at Z = 0.4130 in |
| Largest number size | #1 = 0.2280 in | Less than a quarter of 1 1/16 in |
| Largest letter size | Z = 0.4130 in | Still under half of 1 1/16 in |
The common mistake is assuming every fractional drill has a hidden number or letter alias. Large fractional sizes are listed separately, and no conversion chart will give a match because none exists. To skip the guesswork, a roundup of 1 1/16 inch drill bit options saves hunting.
Practical Notes
A 1 1/16 inch bit is large-diameter, which changes the hardware you need. McMaster-Carr’s ANSI drill bit specifications confirm sizing standards that assume properly rated tools, so check your drill’s chuck capacity and the bit’s shank size first.
Two things trip people up:
- Assortment kits rarely include it. Number and letter assortments stop well below this size; buy it as a single bit or part of a fractional index.
- Tool capacity matters more as diameter grows. A hand drill that spins small bits may struggle in hardwood or metal, so check the drill’s rating and secure the workpiece.
Speed and feed also shift with diameter — larger bits run slower RPM. Follow the manufacturer’s guidance for your tool and material. A 1 1/16 inch bit is 1.0625 in (26.9875 mm), has no number or letter equivalent, and must be bought and used as the fractional size it is.
FAQs
Is there a number drill bit that matches 1 1/16 inch?
No. The number series runs from #80 to #1, which measures 0.2280 in — far smaller. No number size reaches that diameter.
What letter drill bit comes closest to 1 1/16 inch?
None come close. Letter sizes run A through Z, and the largest, Z, is just 0.4130 in — under half. Letter bits are for small-diameter work.
What is 1 1/16 inch in millimeters?
Exactly 26.9875 mm, often rounded to 27.0 mm casually. The difference is negligible except in precision jobs.
References & Sources
- Carbide Processors. “Drill Bit Size Chart” Source for decimal, metric, and number/letter series values, including #1 and A sizes.
- McMaster-Carr. “Drill Bit Charts” Confirms how fractional, number, and letter sizes are organized in standard U.S. charts.
- McMaster-Carr. “ANSI Drill Bits” Reference for ANSI drill bit sizing standards and tool capacity considerations.
