# 63/64" drill size

A 63/64 in drill is 0.9844 in (25.00 mm). It sits between 31/32 in and 1 in in the fractional series; the nearest metric drill is 25.0 mm.

## 63/64" drill data

- Series: Fractional drill
- Decimal: 0.9844 in
- Metric: 25.00 mm (25.0031 mm exact)
- Nearest metric drill: 25.0 mm (−0.003 mm)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 25.0 mm | 0.9843 | −0.003 mm |
| 25.1 mm | 0.9882 | +0.097 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter Z | Letter | 0.4130 | 10.49 |
| 31/32" | Fractional | 0.9688 | 24.61 |
| 63/64" | Fractional | 0.9844 | 25.00 |
| 1" | Fractional | 1.0000 | 25.40 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| M27 × 2 | 25 mm | 77 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| M22 bolt | 22 mm | 3.00 mm | 1.50 mm | Normal fit (normal 24, loose 26 mm) |
| M24 bolt | 24 mm | 1.00 mm | 0.50 mm | Close fit (close 25, normal 26 mm) |


## FAQ

**What size is a 63/64 in drill?**
A 63/64 in drill is 0.9844 in, which is 25.00 mm (25.0031 mm exactly).

**What is the metric equivalent of a 63/64 in drill?**
The nearest metric drill is 25.0 mm, 0.003 mm smaller. The other close size is 25.1 mm.

**What thread can I tap with a 63/64 in drill?**
It leaves about 77 % thread in M27 × 2.

**What does a 63/64 in drill clear?**
It clears a M24 bolt with 1.00 mm total clearance (0.50 mm per side); for metric bolts: close fit.

Source page: https://machinistcharts.com/drill-size/63-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)