# Letter A drill size

A letter A drill is 0.2340 in (5.94 mm). It is the smallest letter drill on this chart; the nearest metric drill is 5.9 mm.

## Letter A drill data

- Series: Letter drill
- Decimal: 0.2340 in
- Metric: 5.94 mm (5.9436 mm exact)
- Nearest metric drill: 5.9 mm (−0.044 mm)
- Nearest fractional: 15/64" (0.2344 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 5.9 mm | 0.2323 | −0.044 mm |
| 6.0 mm | 0.2362 | +0.056 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 7/32" | Fractional | 0.2188 | 5.56 |
| #1 | Number | 0.2280 | 5.79 |
| Letter A | Letter | 0.2340 | 5.94 |
| 15/64" | Fractional | 0.2344 | 5.95 |
| Letter B | Letter | 0.2380 | 6.05 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #10 screw | 0.1900" | 0.0440" | 0.0220" | – |
| #12 screw | 0.2160" | 0.0180" | 0.0090" | – |


## FAQ

**What size is a letter A drill?**
A letter A drill is 0.2340 in, which is 5.94 mm (5.9436 mm exactly).

**What is the metric equivalent of a letter A drill?**
The nearest metric drill is 5.9 mm, 0.044 mm smaller. The other close size is 6.0 mm.

**Which fractional drill is closest to letter A?**
15/64 in (0.2344 in) is the closest, 0.0004 in larger.

**What does a letter A drill clear?**
It clears a #12 screw with 0.0180" total clearance (0.0090" per side).

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