# Letter M drill size

A letter M drill is 0.2950 in (7.49 mm). It sits between letter L and letter N in the letter series; the nearest metric drill is 7.5 mm.

## Letter M drill data

- Series: Letter drill
- Decimal: 0.2950 in
- Metric: 7.49 mm (7.4930 mm exact)
- Nearest metric drill: 7.5 mm (+0.007 mm)
- Nearest fractional: 19/64" (0.2969 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 7.4 mm | 0.2913 | −0.093 mm |
| 7.5 mm | 0.2953 | +0.007 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| 9/32" | Fractional | 0.2812 | 7.14 |
| Letter L | Letter | 0.2900 | 7.37 |
| Letter M | Letter | 0.2950 | 7.49 |
| 19/64" | Fractional | 0.2969 | 7.54 |
| Letter N | Letter | 0.3020 | 7.67 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| 1/4" bolt | 0.2500" | 0.0450" | 0.0225" | – |


## FAQ

**What size is a letter M drill?**
A letter M drill is 0.2950 in, which is 7.49 mm (7.4930 mm exactly).

**What is the metric equivalent of a letter M drill?**
The nearest metric drill is 7.5 mm, 0.007 mm larger. The other close size is 7.4 mm.

**Which fractional drill is closest to letter M?**
19/64 in (0.2969 in) is the closest, 0.0019 in larger.

**What does a letter M drill clear?**
It clears a 1/4" bolt with 0.0450" total clearance (0.0225" per side).

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