#11 drill bit size
0.191 in
4.85 mm · number drill
| Inches | 0.191 in |
| Millimetres | 4.85 mm |
| Nearest metric drill | 4.9 mm |
| System | Number (#1 to #60) |
What #11 means
A bit marked #11 is a number drill, and the number is an index rather than a measurement — the higher the number, the smaller the bit. #1 is 0.228 inches and #60 is 0.04. That is the opposite of the fractional sizes stamped on a home set, which is why a number drill and a fraction of similar appearance can be very different holes.
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 #11:
| System | Nearest size | Difference |
|---|---|---|
| letter | A — 0.234 in | 0.043 in larger |
| fractional | 3/16" — 0.1875 in | 0.0035 in smaller |
| metric | 4.9 mm | 0.049 mm larger |
The closest substitute is 0.0035 inches away. For a clearance hole that is nothing; for a tapping hole it moves the thread engagement by several per cent, which is the difference between an easy tap and a broken one.
What gets drilled at 0.191 inches
The busiest part of the number series. Tapping drills for machine screws from #4 to #12 sit in here, along with pilot holes for wood screws and clearance for small pins. If a number drill in a workshop is worn out, it is usually one of these.
Either side of it
| Drill | Inches | Millimetres |
|---|---|---|
| #13 | 0.185 in | 4.7 mm |
| 3/16" | 0.1875 in | 4.76 mm |
| #12 | 0.189 in | 4.8 mm |
| #11 | 0.191 in | 4.85 mm |
| #10 | 0.1935 in | 4.91 mm |
| #9 | 0.196 in | 4.98 mm |
| #8 | 0.199 in | 5.05 mm |
Frequently asked questions
What size is a #11 drill bit?
0.191 inches, which is 4.85 mm. Number drills run from #1 at 0.228 inches down to #60 at 0.04, getting smaller as the number rises — the opposite of what most people expect the first time.
What is a #11 drill bit in mm?
4.85 mm. A metric index will offer 4.9 mm as the nearest stocked size, which is 0.049 mm larger — enough to matter when tapping and not enough to matter for a clearance hole.
Is #11 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 #11?
#10 at 0.1935 inches — 0.0025 inches larger. Below it is #12 at 0.189.
Other sizes
- #10 drill bit — 0.1935 in, 4.91 mm
- #9 drill bit — 0.196 in, 4.98 mm
- #8 drill bit — 0.199 in, 5.05 mm
- #7 drill bit — 0.201 in, 5.11 mm
- 13/64" drill bit — 0.2031 in, 5.16 mm
- #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