# #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 drill data

- Series: Number drill
- Decimal: 0.1285 in
- Metric: 3.26 mm (3.2639 mm exact)
- Nearest metric drill: 3.3 mm (+0.036 mm)
- Nearest fractional: 1/8" (0.1250 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 3.2 mm | 0.1260 | −0.064 mm |
| 3.3 mm | 0.1299 | +0.036 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #31 | Number | 0.1200 | 3.05 |
| 1/8" | Fractional | 0.1250 | 3.17 |
| #30 | Number | 0.1285 | 3.26 |
| #29 | Number | 0.1360 | 3.45 |
| 9/64" | Fractional | 0.1406 | 3.57 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| M4 × 0.7 | 3.3 mm | 81 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #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" | – |


## FAQ

**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).

Source page: https://machinistcharts.com/drill-size/number-30/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)