# M3.5 tap drill size

The tap drill for an M3.5 × 0.6 metric coarse thread is 2.9 mm (0.1142 in). It leaves about 77 % thread, the normal range for steel.

## Drill options for M3.5 × 0.6

| Drill | Inch | Thread % |
|---|---|---|
| 2.8 mm | 0.1102 | 90 % |
| 2.9 mm | 0.1142 | 77 % |
| 3 mm | 0.1181 | 64 % |
| 3.1 mm | 0.1220 | 51 % |

## M3.5 thread data

- Thread: M3.5 × 0.6 (coarse)
- Pitch: 0.6 mm
- Tap drill: 2.9 mm (0.1142 in)
- Thread engagement: 77 %
- Clearance hole (ISO 273): 3.7 close, 3.9 normal, 4.2 loose (mm)

## Method

Thread % = 76.98 × (D − drill) / P = 76.98 × 0.6 / 0.6 = 77 %. Aim for 65–75 % in steel, 75–85 % in aluminium, brass and plastics.

## FAQ

**What size drill for an M3.5 × 0.6 tap?**
Use a 2.9 mm drill. It leaves about 77 % thread engagement.

**What is 2.9 mm in inches?**
2.9 mm is 0.1142 inch.

**What size clearance hole for M3.5?**
ISO 273 gives 3.7 mm for a close fit, 3.9 mm normal and 4.2 mm loose.

Source page: https://machinistcharts.com/tap-drill/m3-5/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)