# #25 drill size

A #25 drill is 0.1495 in (3.80 mm). It is the standard tap drill for #10-24 UNC; the nearest metric drill is 3.8 mm.

## #25 drill data

- Series: Number drill
- Decimal: 0.1495 in
- Metric: 3.80 mm (3.7973 mm exact)
- Nearest metric drill: 3.8 mm (+0.003 mm)
- Nearest fractional: 5/32" (0.1562 in)
- Standard tap drill for: #10-24 UNC

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 3.7 mm | 0.1457 | −0.097 mm |
| 3.8 mm | 0.1496 | +0.003 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 9/64" | Fractional | 0.1406 | 3.57 |
| #26 | Number | 0.1470 | 3.73 |
| #25 | Number | 0.1495 | 3.80 |
| #24 | Number | 0.1520 | 3.86 |
| 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 | 75 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #3 screw | 0.0990" | 0.0505" | 0.0252" | – |
| #4 screw | 0.1120" | 0.0375" | 0.0187" | – |
| #5 screw | 0.1250" | 0.0245" | 0.0122" | – |
| M3.5 bolt | 3.5 mm | 0.30 mm | 0.15 mm | Close fit (close 3.7, normal 3.9 mm) |
| #6 screw | 0.1380" | 0.0115" | 0.0057" | – |


## FAQ

**What size is a #25 drill?**
A #25 drill is 0.1495 in, which is 3.80 mm (3.7973 mm exactly).

**What is the metric equivalent of a #25 drill?**
The nearest metric drill is 3.8 mm, 0.003 mm larger. The other close size is 3.7 mm.

**What tap uses a #25 drill?**
A #25 drill is the standard tap drill for #10-24 UNC (about 75 % thread).

**Which fractional drill is closest to #25?**
5/32 in (0.1562 in) is the closest, 0.0068 in larger.

**What does a #25 drill clear?**
It clears a #6 screw with 0.0115" total clearance (0.0057" per side).

Source page: https://machinistcharts.com/drill-size/number-25/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)