# M12 tap drill size

The tap drill for an M12 × 1.75 metric coarse thread is 10.2 mm (0.4016 in). It leaves about 79 % thread, the normal range for steel.

## Drill options for M12 × 1.75

| Drill | Inch | Thread % |
|---|---|---|
| 10 mm | 0.3937 | 88 % |
| 10.1 mm | 0.3976 | 84 % |
| 10.2 mm | 0.4016 | 79 % |
| 10.3 mm | 0.4055 | 75 % |
| 10.4 mm | 0.4094 | 70 % |

## M12 thread data

- Thread: M12 × 1.75 (coarse)
- Pitch: 1.75 mm
- Tap drill: 10.2 mm (0.4016 in)
- Thread engagement: 79 %
- Clearance hole (ISO 273): 13 close, 13.5 normal, 14.5 loose (mm)

## Method

Thread % = 76.98 × (D − drill) / P = 76.98 × 1.8 / 1.75 = 79 %. Aim for 65–75 % in steel, 75–85 % in aluminium, brass and plastics.

## FAQ

**What size drill for an M12 × 1.75 tap?**
Use a 10.2 mm drill. It leaves about 79 % thread engagement.

**What is 10.2 mm in inches?**
10.2 mm is 0.4016 inch.

**What size clearance hole for M12?**
ISO 273 gives 13 mm for a close fit, 13.5 mm normal and 14.5 mm loose.

**How tight should an M12 bolt be?**
About 88 N·m for class 8.8 with dry threads.

Source page: https://machinistcharts.com/tap-drill/m12/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)