# #6 drill size

A #6 drill is 0.2040 in (5.18 mm). It sits between #7 and #5 in the number series; the nearest metric drill is 5.2 mm.

## #6 drill data

- Series: Number drill
- Decimal: 0.2040 in
- Metric: 5.18 mm (5.1816 mm exact)
- Nearest metric drill: 5.2 mm (+0.018 mm)
- Nearest fractional: 13/64" (0.2031 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 5.1 mm | 0.2008 | −0.082 mm |
| 5.2 mm | 0.2047 | +0.018 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #7 | Number | 0.2010 | 5.11 |
| 13/64" | Fractional | 0.2031 | 5.16 |
| #6 | Number | 0.2040 | 5.18 |
| #5 | Number | 0.2055 | 5.22 |
| 7/32" | Fractional | 0.2188 | 5.56 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 1/4-20 UNC | #7 | 71 |
| M6 × 0.75 | 5.2 mm | 84 |
| M6 × 1 | 5 mm | 63 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #8 screw | 0.1640" | 0.0400" | 0.0200" | – |
| #10 screw | 0.1900" | 0.0140" | 0.0070" | – |
| M5 bolt | 5 mm | 0.18 mm | 0.09 mm | Tighter than close fit (5.3 mm) |


## FAQ

**What size is a #6 drill?**
A #6 drill is 0.2040 in, which is 5.18 mm (5.1816 mm exactly).

**What is the metric equivalent of a #6 drill?**
The nearest metric drill is 5.2 mm, 0.018 mm larger. The other close size is 5.1 mm.

**What thread can I tap with a #6 drill?**
It leaves about 71 % thread in 1/4-20 UNC and 84 % in M6 × 0.75.

**Which fractional drill is closest to #6?**
13/64 in (0.2031 in) is the closest, 0.0009 in smaller.

**What does a #6 drill clear?**
It clears a M5 bolt with 0.18 mm total clearance (0.09 mm per side); for metric bolts: tighter than close fit.

Source page: https://machinistcharts.com/drill-size/number-6/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)