# #24 drill size

A #24 drill is 0.1520 in (3.86 mm). It sits between #25 and #23 in the number series; the nearest metric drill is 3.9 mm.

## #24 drill data

- Series: Number drill
- Decimal: 0.1520 in
- Metric: 3.86 mm (3.8608 mm exact)
- Nearest metric drill: 3.9 mm (+0.039 mm)
- Nearest fractional: 5/32" (0.1562 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 3.8 mm | 0.1496 | −0.061 mm |
| 3.9 mm | 0.1535 | +0.039 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 9/64" | Fractional | 0.1406 | 3.57 |
| #25 | Number | 0.1495 | 3.80 |
| #24 | Number | 0.1520 | 3.86 |
| #23 | Number | 0.1540 | 3.91 |
| 5/32" | Fractional | 0.1562 | 3.97 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| #10-24 UNC | #25 | 70 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #3 screw | 0.0990" | 0.0530" | 0.0265" | – |
| #4 screw | 0.1120" | 0.0400" | 0.0200" | – |
| #5 screw | 0.1250" | 0.0270" | 0.0135" | – |
| M3.5 bolt | 3.5 mm | 0.36 mm | 0.18 mm | Close fit (close 3.7, normal 3.9 mm) |
| #6 screw | 0.1380" | 0.0140" | 0.0070" | – |


## FAQ

**What size is a #24 drill?**
A #24 drill is 0.1520 in, which is 3.86 mm (3.8608 mm exactly).

**What is the metric equivalent of a #24 drill?**
The nearest metric drill is 3.9 mm, 0.039 mm larger. The other close size is 3.8 mm.

**What thread can I tap with a #24 drill?**
It leaves about 70 % thread in #10-24 UNC.

**Which fractional drill is closest to #24?**
5/32 in (0.1562 in) is the closest, 0.0043 in larger.

**What does a #24 drill clear?**
It clears a #6 screw with 0.0140" total clearance (0.0070" per side).

Source page: https://machinistcharts.com/drill-size/number-24/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)