# M12x1.25 tap drill size

The tap drill for an M12 × 1.25 metric fine thread is 10.8 mm (0.4252 in). It leaves about 74 % thread, the normal range for steel.

## Drill options for M12 × 1.25

| Drill | Inch | Thread % |
|---|---|---|
| 10.6 mm | 0.4173 | 86 % |
| 10.7 mm | 0.4213 | 80 % |
| 10.8 mm | 0.4252 | 74 % |
| 10.9 mm | 0.4291 | 68 % |
| 11 mm | 0.4331 | 62 % |

## M12x1.25 thread data

- Thread: M12 × 1.25 (fine)
- Pitch: 1.25 mm
- Tap drill: 10.8 mm (0.4252 in)
- Thread engagement: 74 %
- Clearance hole (ISO 273): 13 close, 13.5 normal, 14.5 loose (mm)

## Method

Thread % = 76.98 × (D − drill) / P = 76.98 × 1.2 / 1.25 = 74 %. Aim for 65–75 % in steel, 75–85 % in aluminium, brass and plastics.

## FAQ

**What size drill for an M12 × 1.25 tap?**
Use a 10.8 mm drill. It leaves about 74 % thread engagement.

**What is 10.8 mm in inches?**
10.8 mm is 0.4252 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/m12x1-25/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)