# 3/8" drill size

A 3/8 in drill is 0.3750 in (9.52 mm). It sits between 23/64 in and 25/64 in in the fractional series; the nearest metric drill is 9.5 mm.

## 3/8" drill data

- Series: Fractional drill
- Decimal: 0.3750 in
- Metric: 9.52 mm (9.5250 mm exact)
- Nearest metric drill: 9.5 mm (−0.025 mm)
- Nearest letter drill: Letter V (0.3770 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 9.5 mm | 0.3740 | −0.025 mm |
| 9.6 mm | 0.3780 | +0.075 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| 23/64" | Fractional | 0.3594 | 9.13 |
| Letter U | Letter | 0.3680 | 9.35 |
| 3/8" | Fractional | 0.3750 | 9.52 |
| Letter V | Letter | 0.3770 | 9.58 |
| 25/64" | Fractional | 0.3906 | 9.92 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 7/16-14 UNC | U | 67 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| 5/16" bolt | 0.3125" | 0.0625" | 0.0312" | – |
| M8 bolt | 8 mm | 1.52 mm | 0.76 mm | Normal fit (normal 9, loose 10 mm) |


## FAQ

**What size is a 3/8 in drill?**
A 3/8 in drill is 0.3750 in, which is 9.52 mm (9.5250 mm exactly).

**What is the metric equivalent of a 3/8 in drill?**
The nearest metric drill is 9.5 mm, 0.025 mm smaller. The other close size is 9.6 mm.

**What thread can I tap with a 3/8 in drill?**
It leaves about 67 % thread in 7/16-14 UNC.

**Which number or letter drill is closest to 3/8 in?**
Letter V (0.3770 in) is the closest, 0.0020 in larger.

**What does a 3/8 in drill clear?**
It clears a M8 bolt with 1.52 mm total clearance (0.76 mm per side); for metric bolts: normal fit.

Source page: https://machinistcharts.com/drill-size/3-8-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)