# M10x1 tap drill size

The tap drill for an M10 × 1 metric fine thread is 9 mm (0.3543 in). It leaves about 77 % thread, the normal range for steel.

## Drill options for M10 × 1

| Drill | Inch | Thread % |
|---|---|---|
| 8.8 mm | 0.3465 | 92 % |
| 8.9 mm | 0.3504 | 85 % |
| 9 mm | 0.3543 | 77 % |
| 9.1 mm | 0.3583 | 69 % |
| 9.2 mm | 0.3622 | 62 % |

## M10x1 thread data

- Thread: M10 × 1 (fine)
- Pitch: 1 mm
- Tap drill: 9 mm (0.3543 in)
- Thread engagement: 77 %
- Clearance hole (ISO 273): 10.5 close, 11 normal, 12 loose (mm)

## Method

Thread % = 76.98 × (D − drill) / P = 76.98 × 1 / 1 = 77 %. Aim for 65–75 % in steel, 75–85 % in aluminium, brass and plastics.

## FAQ

**What size drill for an M10 × 1 tap?**
Use a 9 mm drill. It leaves about 77 % thread engagement.

**What is 9 mm in inches?**
9 mm is 0.3543 inch.

**What size clearance hole for M10?**
ISO 273 gives 10.5 mm for a close fit, 11 mm normal and 12 mm loose.

**How tight should an M10 bolt be?**
About 50 N·m for class 8.8 with dry threads.

Source page: https://machinistcharts.com/tap-drill/m10x1/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)