# 1/8" drill size

A 1/8 in drill is 0.1250 in (3.17 mm). It sits between 7/64 in and 9/64 in in the fractional series; the nearest metric drill is 3.2 mm.

## 1/8" drill data

- Series: Fractional drill
- Decimal: 0.1250 in
- Metric: 3.17 mm (3.1750 mm exact)
- Nearest metric drill: 3.2 mm (+0.025 mm)
- Nearest number drill: #30 (0.1285 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 3.1 mm | 0.1220 | −0.075 mm |
| 3.2 mm | 0.1260 | +0.025 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 7/64" | Fractional | 0.1094 | 2.78 |
| #31 | Number | 0.1200 | 3.05 |
| 1/8" | Fractional | 0.1250 | 3.17 |
| #30 | Number | 0.1285 | 3.26 |
| 9/64" | Fractional | 0.1406 | 3.57 |
| Letter A | Letter | 0.2340 | 5.94 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #1 screw | 0.0730" | 0.0520" | 0.0260" | – |
| #2 screw | 0.0860" | 0.0390" | 0.0195" | – |
| #3 screw | 0.0990" | 0.0260" | 0.0130" | – |
| #4 screw | 0.1120" | 0.0130" | 0.0065" | – |
| M3 bolt | 3 mm | 0.17 mm | 0.09 mm | Tighter than close fit (3.2 mm) |


## FAQ

**What size is a 1/8 in drill?**
A 1/8 in drill is 0.1250 in, which is 3.17 mm (3.1750 mm exactly).

**What is the metric equivalent of a 1/8 in drill?**
The nearest metric drill is 3.2 mm, 0.025 mm larger. The other close size is 3.1 mm.

**Which number or letter drill is closest to 1/8 in?**
#30 (0.1285 in) is the closest, 0.0035 in larger.

**What does a 1/8 in drill clear?**
It clears a M3 bolt with 0.17 mm total clearance (0.09 mm per side); for metric bolts: tighter than close fit.

Source page: https://machinistcharts.com/drill-size/1-8-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)