# 7/16-20 tap drill size

The tap drill for a 7/16-20 UNF thread is a 25/64 drill (0.3906 in, 9.92 mm). It leaves about 72 % thread. The closest metric drill is 9.9 mm, which leaves 73 % thread.

## Drill options for 7/16-20 UNF

| Drill | Inch | Thread % |
|---|---|---|
| 25/64 | 0.3906 | 72 % |
| 9.8 mm | 0.3858 | 80 % |
| 9.9 mm | 0.3898 | 73 % |
| 10.0 mm | 0.3937 | 67 % |

## 7/16-20 thread data

- Thread: 7/16-20 UNF, 20 TPI
- Major diameter: 0.4375 in (11.11 mm)
- Tap drill: 25/64 = 0.3906 in (9.92 mm)
- Thread engagement: 72 %

## Method

Thread % = TPI × (D − drill) / 0.01299 = 20 × 0.0469 / 0.01299 = 72 %.

## FAQ

**What size drill for a 7/16-20 tap?**
Use a 25/64 drill (0.3906 in, 9.92 mm). It leaves about 72 % thread.

**Can I use a metric drill for 7/16-20?**
Yes. A 9.9 mm drill gives about 73 % thread.

**How tight should a 7/16 grade 5 bolt be?**
About 55 ft-lb dry for 7/16-20 UNF.

Source page: https://machinistcharts.com/tap-drill/7-16-20/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)