# 1/2" drill size

A 1/2 in drill is 0.5000 in (12.70 mm). It sits between 31/64 in and 33/64 in in the fractional series; the nearest metric drill is 12.7 mm.

## 1/2" drill data

- Series: Fractional drill
- Decimal: 0.5000 in
- Metric: 12.70 mm (12.7000 mm exact)
- Nearest metric drill: 12.7 mm (0 mm)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 12.6 mm | 0.4961 | −0.100 mm |
| 12.7 mm | 0.5000 | 0 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter Z | Letter | 0.4130 | 10.49 |
| 31/64" | Fractional | 0.4844 | 12.30 |
| 1/2" | Fractional | 0.5000 | 12.70 |
| 33/64" | Fractional | 0.5156 | 13.10 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| M14 × 1.5 | 12.5 mm | 67 |
| 9/16-12 UNC | 31/64 | 58 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| 7/16" bolt | 0.4375" | 0.0625" | 0.0312" | – |
| M12 bolt | 12 mm | 0.70 mm | 0.35 mm | Tighter than close fit (13 mm) |


## FAQ

**What size is a 1/2 in drill?**
A 1/2 in drill is 0.5000 in, which is 12.70 mm (12.7000 mm exactly).

**What is the metric equivalent of a 1/2 in drill?**
The nearest metric drill is 12.7 mm, 0.000 mm smaller. The other close size is 12.6 mm.

**What thread can I tap with a 1/2 in drill?**
It leaves about 67 % thread in M14 × 1.5 and 58 % in 9/16-12 UNC.

**What does a 1/2 in drill clear?**
It clears a M12 bolt with 0.70 mm total clearance (0.35 mm per side); for metric bolts: tighter than close fit.

Source page: https://machinistcharts.com/drill-size/1-2-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)