# #7 drill size

A #7 drill is 0.2010 in (5.11 mm). It is the standard tap drill for 1/4-20 UNC; the nearest metric drill is 5.1 mm.

## #7 drill data

- Series: Number drill
- Decimal: 0.2010 in
- Metric: 5.11 mm (5.1054 mm exact)
- Nearest metric drill: 5.1 mm (−0.005 mm)
- Nearest fractional: 13/64" (0.2031 in)
- Standard tap drill for: 1/4-20 UNC

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 5.1 mm | 0.2008 | −0.005 mm |
| 5.2 mm | 0.2047 | +0.095 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 3/16" | Fractional | 0.1875 | 4.76 |
| #8 | Number | 0.1990 | 5.05 |
| #7 | Number | 0.2010 | 5.11 |
| 13/64" | Fractional | 0.2031 | 5.16 |
| #6 | Number | 0.2040 | 5.18 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 1/4-20 UNC | #7 | 75 |
| M6 × 1 | 5 mm | 69 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #8 screw | 0.1640" | 0.0370" | 0.0185" | – |
| #10 screw | 0.1900" | 0.0110" | 0.0055" | – |
| M5 bolt | 5 mm | 0.11 mm | 0.05 mm | Tighter than close fit (5.3 mm) |


## FAQ

**What size is a #7 drill?**
A #7 drill is 0.2010 in, which is 5.11 mm (5.1054 mm exactly).

**What is the metric equivalent of a #7 drill?**
The nearest metric drill is 5.1 mm, 0.005 mm smaller. The other close size is 5.2 mm.

**What tap uses a #7 drill?**
A #7 drill is the standard tap drill for 1/4-20 UNC (about 75 % thread).

**Which fractional drill is closest to #7?**
13/64 in (0.2031 in) is the closest, 0.0021 in larger.

**What does a #7 drill clear?**
It clears a M5 bolt with 0.11 mm total clearance (0.05 mm per side); for metric bolts: tighter than close fit.

Source page: https://machinistcharts.com/drill-size/number-7/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)