# Letter N drill size

A letter N drill is 0.3020 in (7.67 mm). It sits between letter M and letter O in the letter series; the nearest metric drill is 7.7 mm.

## Letter N drill data

- Series: Letter drill
- Decimal: 0.3020 in
- Metric: 7.67 mm (7.6708 mm exact)
- Nearest metric drill: 7.7 mm (+0.029 mm)
- Nearest fractional: 19/64" (0.2969 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 7.6 mm | 0.2992 | −0.071 mm |
| 7.7 mm | 0.3031 | +0.029 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter M | Letter | 0.2950 | 7.49 |
| 19/64" | Fractional | 0.2969 | 7.54 |
| Letter N | Letter | 0.3020 | 7.67 |
| 5/16" | Fractional | 0.3125 | 7.94 |
| Letter O | Letter | 0.3160 | 8.03 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| 1/4" bolt | 0.2500" | 0.0520" | 0.0260" | – |


## FAQ

**What size is a letter N drill?**
A letter N drill is 0.3020 in, which is 7.67 mm (7.6708 mm exactly).

**What is the metric equivalent of a letter N drill?**
The nearest metric drill is 7.7 mm, 0.029 mm larger. The other close size is 7.6 mm.

**Which fractional drill is closest to letter N?**
19/64 in (0.2969 in) is the closest, 0.0051 in smaller.

**What does a letter N drill clear?**
It clears a 1/4" bolt with 0.0520" total clearance (0.0260" per side).

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