13/64" drill bit size
0.2031 in
5.16 mm · fractional drill
| Inches | 0.2031 in |
| Millimetres | 5.16 mm |
| Nearest metric drill | 5.2 mm |
| System | Fractional (64ths) |
What 13/64" means
13/64" 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 13/64":
| System | Nearest size | Difference |
|---|---|---|
| number | #6 — 0.204 in | 0.0009 in larger |
| letter | A — 0.234 in | 0.0309 in larger |
| metric | 5.2 mm | 0.041 mm larger |
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 0.2031 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 |
|---|---|---|
| #9 | 0.196 in | 4.98 mm |
| #8 | 0.199 in | 5.05 mm |
| #7 | 0.201 in | 5.11 mm |
| 13/64" | 0.2031 in | 5.16 mm |
| #6 | 0.204 in | 5.18 mm |
| #5 | 0.2055 in | 5.22 mm |
| #4 | 0.209 in | 5.31 mm |
Frequently asked questions
What size is a 13/64" drill bit?
0.2031 inches, which is 5.16 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 13/64" drill bit in mm?
5.16 mm. A metric index will offer 5.2 mm as the nearest stocked size, which is 0.041 mm larger — enough to matter when tapping and not enough to matter for a clearance hole.
Is 13/64" 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 13/64"?
#6 at 0.204 inches — 0.0009 inches larger. Below it is #7 at 0.201.
Other sizes
- #6 drill bit — 0.204 in, 5.18 mm
- #5 drill bit — 0.2055 in, 5.22 mm
- #4 drill bit — 0.209 in, 5.31 mm
- #3 drill bit — 0.213 in, 5.41 mm
- 7/32" drill bit — 0.2188 in, 5.56 mm
- #2 drill bit — 0.221 in, 5.61 mm
- #1 drill bit — 0.228 in, 5.79 mm
- A drill bit — 0.234 in, 5.94 mm