# M16x1.5 tap drill size

The tap drill for an M16 × 1.5 metric fine thread is 14.5 mm (0.5709 in). It leaves about 77 % thread, the normal range for steel.

## Drill options for M16 × 1.5

| Drill | Inch | Thread % |
|---|---|---|
| 14.3 mm | 0.5630 | 87 % |
| 14.4 mm | 0.5669 | 82 % |
| 14.5 mm | 0.5709 | 77 % |
| 14.6 mm | 0.5748 | 72 % |
| 14.7 mm | 0.5787 | 67 % |

## M16x1.5 thread data

- Thread: M16 × 1.5 (fine)
- Pitch: 1.5 mm
- Tap drill: 14.5 mm (0.5709 in)
- Thread engagement: 77 %
- Clearance hole (ISO 273): 17 close, 17.5 normal, 18.5 loose (mm)

## Method

Thread % = 76.98 × (D − drill) / P = 76.98 × 1.5 / 1.5 = 77 %. Aim for 65–75 % in steel, 75–85 % in aluminium, brass and plastics.

## FAQ

**What size drill for an M16 × 1.5 tap?**
Use a 14.5 mm drill. It leaves about 77 % thread engagement.

**What is 14.5 mm in inches?**
14.5 mm is 0.5709 inch.

**What size clearance hole for M16?**
ISO 273 gives 17 mm for a close fit, 17.5 mm normal and 18.5 mm loose.

**How tight should an M16 bolt be?**
About 218 N·m for class 8.8 with dry threads.

Source page: https://machinistcharts.com/tap-drill/m16x1-5/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)