# 59/64" drill size

A 59/64 in drill is 0.9219 in (23.42 mm). It is the standard tap drill for 1-12 UNF; the nearest metric drill is 23.4 mm.

## 59/64" drill data

- Series: Fractional drill
- Decimal: 0.9219 in
- Metric: 23.42 mm (23.4156 mm exact)
- Nearest metric drill: 23.4 mm (−0.016 mm)
- Standard tap drill for: 1-12 UNF

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 23.4 mm | 0.9213 | −0.016 mm |
| 23.5 mm | 0.9252 | +0.084 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter Z | Letter | 0.4130 | 10.49 |
| 29/32" | Fractional | 0.9062 | 23.02 |
| 59/64" | Fractional | 0.9219 | 23.42 |
| 15/16" | Fractional | 0.9375 | 23.81 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 1-12 UNF | 59/64 | 72 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| M20 bolt | 20 mm | 3.42 mm | 1.71 mm | Normal fit (normal 22, loose 24 mm) |
| M22 bolt | 22 mm | 1.42 mm | 0.71 mm | Close fit (close 23, normal 24 mm) |
| 7/8" bolt | 0.8750" | 0.0469" | 0.0234" | – |


## FAQ

**What size is a 59/64 in drill?**
A 59/64 in drill is 0.9219 in, which is 23.42 mm (23.4156 mm exactly).

**What is the metric equivalent of a 59/64 in drill?**
The nearest metric drill is 23.4 mm, 0.016 mm smaller. The other close size is 23.5 mm.

**What tap uses a 59/64 in drill?**
A 59/64 in drill is the standard tap drill for 1-12 UNF (about 72 % thread).

**What does a 59/64 in drill clear?**
It clears a 7/8" bolt with 0.0469" total clearance (0.0234" per side).

Source page: https://machinistcharts.com/drill-size/59-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)