# 39/64" drill size

A 39/64 in drill is 0.6094 in (15.48 mm). It sits between 19/32 in and 5/8 in in the fractional series; the nearest metric drill is 15.5 mm.

## 39/64" drill data

- Series: Fractional drill
- Decimal: 0.6094 in
- Metric: 15.48 mm (15.4781 mm exact)
- Nearest metric drill: 15.5 mm (+0.022 mm)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 15.4 mm | 0.6063 | −0.078 mm |
| 15.5 mm | 0.6102 | +0.022 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter Z | Letter | 0.4130 | 10.49 |
| 19/32" | Fractional | 0.5938 | 15.08 |
| 39/64" | Fractional | 0.6094 | 15.48 |
| 5/8" | Fractional | 0.6250 | 15.88 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| M18 × 2.5 | 15.5 mm | 78 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| M14 bolt | 14 mm | 1.48 mm | 0.74 mm | Close fit (close 15, normal 15.5 mm) |
| 9/16" bolt | 0.5625" | 0.0469" | 0.0234" | – |


## FAQ

**What size is a 39/64 in drill?**
A 39/64 in drill is 0.6094 in, which is 15.48 mm (15.4781 mm exactly).

**What is the metric equivalent of a 39/64 in drill?**
The nearest metric drill is 15.5 mm, 0.022 mm larger. The other close size is 15.4 mm.

**What thread can I tap with a 39/64 in drill?**
It leaves about 78 % thread in M18 × 2.5.

**What does a 39/64 in drill clear?**
It clears a 9/16" bolt with 0.0469" total clearance (0.0234" per side).

Source page: https://machinistcharts.com/drill-size/39-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)