# 1/64" drill size

A 1/64 in drill is 0.0156 in (0.40 mm). It is the smallest fractional drill on this chart; the nearest metric drill is 0.4 mm.

## 1/64" drill data

- Series: Fractional drill
- Decimal: 0.0156 in
- Metric: 0.40 mm (0.3969 mm exact)
- Nearest metric drill: 0.4 mm (+0.003 mm)
- Nearest number drill: #78 (0.0160 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 0.35 mm | 0.0138 | −0.047 mm |
| 0.4 mm | 0.0157 | +0.003 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #79 | Number | 0.0145 | 0.37 |
| 1/64" | Fractional | 0.0156 | 0.40 |
| #78 | Number | 0.0160 | 0.41 |
| 1/32" | Fractional | 0.0312 | 0.79 |
| Letter A | Letter | 0.2340 | 5.94 |


## FAQ

**What size is a 1/64 in drill?**
A 1/64 in drill is 0.0156 in, which is 0.40 mm (0.3969 mm exactly).

**What is the metric equivalent of a 1/64 in drill?**
The nearest metric drill is 0.4 mm, 0.003 mm larger. The other close size is 0.35 mm.

**Which number or letter drill is closest to 1/64 in?**
#78 (0.0160 in) is the closest, 0.0004 in larger.

Source page: https://machinistcharts.com/drill-size/1-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)