# 49/64" drill size

A 49/64 in drill is 0.7656 in (19.45 mm). It is the standard tap drill for 7/8-9 UNC; the nearest metric drill is 19.4 mm.

## 49/64" drill data

- Series: Fractional drill
- Decimal: 0.7656 in
- Metric: 19.45 mm (19.4469 mm exact)
- Nearest metric drill: 19.4 mm (−0.047 mm)
- Standard tap drill for: 7/8-9 UNC

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 19.4 mm | 0.7638 | −0.047 mm |
| 19.5 mm | 0.7677 | +0.053 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| #1 | Number | 0.2280 | 5.79 |
| Letter Z | Letter | 0.4130 | 10.49 |
| 3/4" | Fractional | 0.7500 | 19.05 |
| 49/64" | Fractional | 0.7656 | 19.45 |
| 25/32" | Fractional | 0.7812 | 19.84 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| 7/8-9 UNC | 49/64 | 76 |
| M22 × 2.5 | 19.5 mm | 79 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| M18 bolt | 18 mm | 1.45 mm | 0.72 mm | Close fit (close 19, normal 20 mm) |
| 3/4" bolt | 0.7500" | 0.0156" | 0.0078" | – |


## FAQ

**What size is a 49/64 in drill?**
A 49/64 in drill is 0.7656 in, which is 19.45 mm (19.4469 mm exactly).

**What is the metric equivalent of a 49/64 in drill?**
The nearest metric drill is 19.4 mm, 0.047 mm smaller. The other close size is 19.5 mm.

**What tap uses a 49/64 in drill?**
A 49/64 in drill is the standard tap drill for 7/8-9 UNC (about 76 % thread).

**What does a 49/64 in drill clear?**
It clears a 3/4" bolt with 0.0156" total clearance (0.0078" per side).

Source page: https://machinistcharts.com/drill-size/49-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)