# #3 drill size

A #3 drill is 0.2130 in (5.41 mm). It is the standard tap drill for 1/4-28 UNF; the nearest metric drill is 5.4 mm.

## #3 drill data

- Series: Number drill
- Decimal: 0.2130 in
- Metric: 5.41 mm (5.4102 mm exact)
- Nearest metric drill: 5.4 mm (−0.010 mm)
- Nearest fractional: 7/32" (0.2188 in)
- Standard tap drill for: 1/4-28 UNF

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 5.4 mm | 0.2126 | −0.010 mm |
| 5.5 mm | 0.2165 | +0.090 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 13/64" | Fractional | 0.2031 | 5.16 |
| #4 | Number | 0.2090 | 5.31 |
| #3 | Number | 0.2130 | 5.41 |
| 7/32" | Fractional | 0.2188 | 5.56 |
| #2 | Number | 0.2210 | 5.61 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 1/4-28 UNF | #3 | 80 |
| M6 × 0.75 | 5.2 mm | 61 |
| 1/4-20 UNC | #7 | 57 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #8 screw | 0.1640" | 0.0490" | 0.0245" | – |
| #10 screw | 0.1900" | 0.0230" | 0.0115" | – |
| M5 bolt | 5 mm | 0.41 mm | 0.21 mm | Close fit (close 5.3, normal 5.5 mm) |


## FAQ

**What size is a #3 drill?**
A #3 drill is 0.2130 in, which is 5.41 mm (5.4102 mm exactly).

**What is the metric equivalent of a #3 drill?**
The nearest metric drill is 5.4 mm, 0.010 mm smaller. The other close size is 5.5 mm.

**What tap uses a #3 drill?**
A #3 drill is the standard tap drill for 1/4-28 UNF (about 80 % thread).

**Which fractional drill is closest to #3?**
7/32 in (0.2188 in) is the closest, 0.0058 in larger.

**What does a #3 drill clear?**
It clears a M5 bolt with 0.41 mm total clearance (0.21 mm per side); for metric bolts: close fit.

Source page: https://machinistcharts.com/drill-size/number-3/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)