17/64" drill bit size
0.2656 in
6.75 mm · fractional drill
| Inches | 0.2656 in |
| Millimetres | 6.75 mm |
| Nearest metric drill | 6.7 mm |
| System | Fractional (64ths) |
What 17/64" means
17/64" is a fractional drill, stepping in 64ths of an inch. Fractional sizes are the coarsest of the three systems, which is why a fractional set alone cannot hit most tapping sizes and why number and letter drills exist at all.
The same hole in the other systems
Three drill systems overlap across this range and a workshop rarely has all three. The nearest bit of each other kind to 17/64":
| System | Nearest size | Difference |
|---|---|---|
| number | #1 — 0.228 in | 0.0376 in smaller |
| letter | H — 0.266 in | 0.0004 in larger |
| metric | 6.7 mm | 0.047 mm smaller |
One of those is within three thousandths of an inch, which is inside the tolerance of most hand-held work — substitute it and nobody will know.
What gets drilled at 0.2656 inches
Where the quarter-inch and five-sixteenths taps are drilled, and where clearance holes for small bolts begin. The three drill systems overlap most densely across this band, which is why a bit here is the one most often picked up and misidentified.
Either side of it
| Drill | Inches | Millimetres |
|---|---|---|
| 1/4" | 0.25 in | 6.35 mm |
| F | 0.257 in | 6.53 mm |
| G | 0.261 in | 6.63 mm |
| 17/64" | 0.2656 in | 6.75 mm |
| H | 0.266 in | 6.76 mm |
| I | 0.272 in | 6.91 mm |
| J | 0.277 in | 7.04 mm |
Frequently asked questions
What size is a 17/64" drill bit?
0.2656 inches, which is 6.75 mm. Fractional drills step in 64ths of an inch, which is the coarsest of the three systems and the one most home sets contain.
What is a 17/64" drill bit in mm?
6.75 mm. A metric index will offer 6.7 mm as the nearest stocked size, which is 0.047 mm smaller — enough to matter when tapping and not enough to matter for a clearance hole.
Is 17/64" a tapping drill size?
Not for any of the unified threads on this site. It sits between the sizes the standard taps call for, so it is a clearance or pilot drill rather than a tapping one.
What is the next size up from 17/64"?
H at 0.266 inches — 0.0004 inches larger. Below it is G at 0.261.
Other sizes
- H drill bit — 0.266 in, 6.76 mm
- I drill bit — 0.272 in, 6.91 mm
- J drill bit — 0.277 in, 7.04 mm
- K drill bit — 0.281 in, 7.14 mm
- 9/32" drill bit — 0.2813 in, 7.14 mm
- L drill bit — 0.29 in, 7.37 mm
- M drill bit — 0.295 in, 7.49 mm
- 19/64" drill bit — 0.2969 in, 7.54 mm