# 29/64" drill size

A 29/64 in drill is 0.4531 in (11.51 mm). It is the standard tap drill for 1/2-20 UNF; the nearest metric drill is 11.5 mm.

## 29/64" drill data

- Series: Fractional drill
- Decimal: 0.4531 in
- Metric: 11.51 mm (11.5094 mm exact)
- Nearest metric drill: 11.5 mm (−0.009 mm)
- Standard tap drill for: 1/2-20 UNF

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 11.5 mm | 0.4528 | −0.009 mm |
| 11.6 mm | 0.4567 | +0.091 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter Z | Letter | 0.4130 | 10.49 |
| 7/16" | Fractional | 0.4375 | 11.11 |
| 29/64" | Fractional | 0.4531 | 11.51 |
| 15/32" | Fractional | 0.4688 | 11.91 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 1/2-20 UNF | 29/64 | 72 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| M10 bolt | 10 mm | 1.51 mm | 0.75 mm | Normal fit (normal 11, loose 12 mm) |
| 7/16" bolt | 0.4375" | 0.0156" | 0.0078" | – |


## FAQ

**What size is a 29/64 in drill?**
A 29/64 in drill is 0.4531 in, which is 11.51 mm (11.5094 mm exactly).

**What is the metric equivalent of a 29/64 in drill?**
The nearest metric drill is 11.5 mm, 0.009 mm smaller. The other close size is 11.6 mm.

**What tap uses a 29/64 in drill?**
A 29/64 in drill is the standard tap drill for 1/2-20 UNF (about 72 % thread).

**What does a 29/64 in drill clear?**
It clears a 7/16" bolt with 0.0156" total clearance (0.0078" per side).

Source page: https://machinistcharts.com/drill-size/29-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)