# #42 drill size

A #42 drill is 0.0935 in (2.37 mm). It is the standard tap drill for #4-48 UNF; the nearest metric drill is 2.35 mm.

## #42 drill data

- Series: Number drill
- Decimal: 0.0935 in
- Metric: 2.37 mm (2.3749 mm exact)
- Nearest metric drill: 2.35 mm (−0.025 mm)
- Nearest fractional: 3/32" (0.0938 in)
- Standard tap drill for: #4-48 UNF

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 2.35 mm | 0.0925 | −0.025 mm |
| 2.4 mm | 0.0945 | +0.025 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 5/64" | Fractional | 0.0781 | 1.98 |
| #43 | Number | 0.0890 | 2.26 |
| #42 | Number | 0.0935 | 2.37 |
| 3/32" | Fractional | 0.0938 | 2.38 |
| #41 | Number | 0.0960 | 2.44 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| #4-48 UNF | #42 | 68 |
| #4-40 UNC | #43 | 57 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #1 screw | 0.0730" | 0.0205" | 0.0103" | – |
| M2 bolt | 2 mm | 0.37 mm | 0.19 mm | Close fit (close 2.2, normal 2.4 mm) |
| #2 screw | 0.0860" | 0.0075" | 0.0038" | – |


## FAQ

**What size is a #42 drill?**
A #42 drill is 0.0935 in, which is 2.37 mm (2.3749 mm exactly).

**What is the metric equivalent of a #42 drill?**
The nearest metric drill is 2.35 mm, 0.025 mm smaller. The other close size is 2.4 mm.

**What tap uses a #42 drill?**
A #42 drill is the standard tap drill for #4-48 UNF (about 68 % thread).

**Which fractional drill is closest to #42?**
3/32 in (0.0938 in) is the closest, 0.0003 in larger.

**What does a #42 drill clear?**
It clears a #2 screw with 0.0075" total clearance (0.0038" per side).

Source page: https://machinistcharts.com/drill-size/number-42/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)