# #1 drill size

A #1 drill is 0.2280 in (5.79 mm). It is the largest number drill on this chart; the nearest metric drill is 5.8 mm.

## #1 drill data

- Series: Number drill
- Decimal: 0.2280 in
- Metric: 5.79 mm (5.7912 mm exact)
- Nearest metric drill: 5.8 mm (+0.009 mm)
- Nearest fractional: 15/64" (0.2344 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 5.7 mm | 0.2244 | −0.091 mm |
| 5.8 mm | 0.2283 | +0.009 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 7/32" | Fractional | 0.2188 | 5.56 |
| #2 | Number | 0.2210 | 5.61 |
| #1 | Number | 0.2280 | 5.79 |
| Letter A | Letter | 0.2340 | 5.94 |
| 15/64" | Fractional | 0.2344 | 5.95 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #10 screw | 0.1900" | 0.0380" | 0.0190" | – |
| M5 bolt | 5 mm | 0.79 mm | 0.40 mm | Normal fit (normal 5.5, loose 5.8 mm) |
| #12 screw | 0.2160" | 0.0120" | 0.0060" | – |


## FAQ

**What size is a #1 drill?**
A #1 drill is 0.2280 in, which is 5.79 mm (5.7912 mm exactly).

**What is the metric equivalent of a #1 drill?**
The nearest metric drill is 5.8 mm, 0.009 mm larger. The other close size is 5.7 mm.

**Which fractional drill is closest to #1?**
15/64 in (0.2344 in) is the closest, 0.0064 in larger.

**What does a #1 drill clear?**
It clears a #12 screw with 0.0120" total clearance (0.0060" per side).

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