#30 drill size
A #30 drill is 0.1285 in (3.26 mm). It sits between #31 and #29 in the number series; the nearest metric drill is 3.3 mm.
#30 at a glance
Decimal, metric and the nearest sizes in the other series.
Nearest metric drills
Metric drills step by 0.05 mm below 3 mm and by 0.1 mm from 3 mm. Difference is metric minus inch size.
| Metric drill | Inch | Difference | In inches | Hole |
|---|---|---|---|---|
| 3.2 mm | 0.1260" | −0.064 mm | −0.0025" | Smaller |
| 3.3 mm | 0.1299" | +0.036 mm | +0.0014" | Larger |
Nearby inch drills
The next size down and up in each inch series, so you can pick a substitute from the drawer.
Threads a #30 drill can tap
Threads from the tap tables on this site that this drill can tap, with the thread percentage it leaves (55–85 % shown).
| Thread | Standard drill | Thread with this drill | Suits |
|---|---|---|---|
| M4 × 0.7 | 3.3 mm | 81 % | Soft metals, plastics |
Clearance for screws and bolts
Bolts and screws a #30 hole clears, with the diametral clearance and the gap each side. Metric sizes are compared with ISO 273.
| Fastener | Diameter | Clearance | Per side | ISO 273, metric only |
|---|---|---|---|---|
| #1 screw | 0.0730" | 0.0555" | 0.0278" | – |
| #2 screw | 0.0860" | 0.0425" | 0.0213" | – |
| #3 screw | 0.0990" | 0.0295" | 0.0147" | – |
| #4 screw | 0.1120" | 0.0165" | 0.0083" | – |
| M3 bolt | 3 mm | 0.26 mm | 0.13 mm | Close fit (close 3.2, normal 3.4 mm) |
| #5 screw | 0.1250" | 0.0035" | 0.0018" | – |
Inch clearance is the drill size minus the basic major diameter. A drilled hole usually cuts slightly oversize.
Number drill index
Every size in the series, holes drawn to scale.
Common questions
What size is a #30 drill?
A #30 drill is 0.1285 in, which is 3.26 mm (3.2639 mm exactly).
What is the metric equivalent of a #30 drill?
The nearest metric drill is 3.3 mm, 0.036 mm larger. The other close size is 3.2 mm.
What thread can I tap with a #30 drill?
It leaves about 81 % thread in M4 × 0.7.
Which fractional drill is closest to #30?
1/8 in (0.1250 in) is the closest, 0.0035 in smaller.
What does a #30 drill clear?
It clears a #5 screw with 0.0035" total clearance (0.0018" per side).