# 9/64" drill size

A 9/64 in drill is 0.1406 in (3.57 mm). It sits between 1/8 in and 5/32 in in the fractional series; the nearest metric drill is 3.6 mm.

## 9/64" drill data

- Series: Fractional drill
- Decimal: 0.1406 in
- Metric: 3.57 mm (3.5719 mm exact)
- Nearest metric drill: 3.6 mm (+0.028 mm)
- Nearest number drill: #28 (0.1405 in)

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 3.5 mm | 0.1378 | −0.072 mm |
| 3.6 mm | 0.1417 | +0.028 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 1/8" | Fractional | 0.1250 | 3.17 |
| #28 | Number | 0.1405 | 3.57 |
| 9/64" | Fractional | 0.1406 | 3.57 |
| #27 | Number | 0.1440 | 3.66 |
| 5/32" | Fractional | 0.1562 | 3.97 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| M4 × 0.5 | 3.5 mm | 66 |
| #8-36 UNF | #29 | 65 |
| #8-32 UNC | #29 | 58 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #2 screw | 0.0860" | 0.0546" | 0.0273" | – |
| #3 screw | 0.0990" | 0.0416" | 0.0208" | – |
| #4 screw | 0.1120" | 0.0286" | 0.0143" | – |
| M3 bolt | 3 mm | 0.57 mm | 0.29 mm | Normal fit (normal 3.4, loose 3.6 mm) |
| #5 screw | 0.1250" | 0.0156" | 0.0078" | – |
| M3.5 bolt | 3.5 mm | 0.07 mm | 0.04 mm | Tighter than close fit (3.7 mm) |
| #6 screw | 0.1380" | 0.0026" | 0.0013" | – |


## FAQ

**What size is a 9/64 in drill?**
A 9/64 in drill is 0.1406 in, which is 3.57 mm (3.5719 mm exactly).

**What is the metric equivalent of a 9/64 in drill?**
The nearest metric drill is 3.6 mm, 0.028 mm larger. The other close size is 3.5 mm.

**What thread can I tap with a 9/64 in drill?**
It leaves about 66 % thread in M4 × 0.5 and 65 % in #8-36 UNF.

**Which number or letter drill is closest to 9/64 in?**
#28 (0.1405 in) is the closest, 0.0001 in smaller.

**What does a 9/64 in drill clear?**
It clears a #6 screw with 0.0026" total clearance (0.0013" per side).

Source page: https://machinistcharts.com/drill-size/9-64-inch/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)