---
title: "M16×2 tap drill 14 mm, clearance 17 mm"
description: "M16×2: tap drill 14 mm, clearance hole 17 mm, 24 mm hex. Full thread dimensions, how to identify it, and torque."
url: https://atoneplace.net/fastener/m16-2/
site: "At One Place"
---

# M16×2 thread

**M16×2 tap drill: 14 mm**

Clearance hole 17 mm · 24 mm hex

M16×2 is a coarse metric thread with a 16 mm (0.630") major diameter and 2 mm pitch. Tap it with a 14 mm drill; drill 17 mm to pass a bolt through.

## The numbers

- **Designation:** M16×2
- **Major diameter:** 16 mm / 0.630"
- **Minor diameter:** 13.835 mm
- **Pitch:** 2 mm pitch
- **Tap drill (75% thread):** 14 mm — 14 mm
- **Clearance hole (close fit):** 17 mm / 0.669"
- **Hex across flats:** 24 mm

## How to measure what you have

1. Measure across the thread crests with calipers. A used M16×2 reads a little under 16 mm — the crests are truncated by the standard, then worn and plated, so anything from about 15.6 mm up is consistent with this size.
2. Measure the pitch: put a rule against the threads and count the distance over ten crests, then divide by ten. This one should give 2 mm.
3. A thread pitch gauge settles it in seconds and costs very little. Guessing between a coarse and a fine thread of the same diameter is the usual way a thread gets stripped.

## Tightening torque

**Typical torque: 180–240 N·m**

132.8–177.0 lb·ft

> Plain steel property class 8.8 or SAE grade 5, dry threads, tightened to about 65% of yield. Lubricated threads reach the same preload at 20-30% less torque. Where the manufacturer publishes a figure — spark plugs, wheel nuts, cylinder heads — use theirs.

## Where this size turns up

- Structural steelwork and baseplate holding-down bolts
- Tow hooks and recovery eyes
- Heavy machinery mounting feet

## Other threads at this diameter

*Same diameter, different pitch. Forcing the wrong one strips the thread in a turn or two.*

| Thread | Pitch | Tap drill | Clearance |
| --- | --- | --- | --- |
| M16×1.5 | 1.5 mm | 14.5 mm | 17 mm |

## Common questions

### What size drill for an M16×2 tap?

14 mm (14 mm), which gives about 75% thread engagement.

### What clearance hole for M16×2?

17 mm for a close fit — enough to pass the bolt without slop.

### What spanner fits M16×2?

24 mm across the flats on a standard hex head.

## Related pages

- [M16×1.5](https://atoneplace.net/fastener/m16-1-5/)
- [M14×2](https://atoneplace.net/fastener/m14-2/)
- [M18×2.5](https://atoneplace.net/fastener/m18-2-5/)
- [M14×1.5](https://atoneplace.net/fastener/m14-1-5/)
- [M14×1.25](https://atoneplace.net/fastener/m14-1-25/)
- [M18×1.5](https://atoneplace.net/fastener/m18-1-5/)
- [M12×1.75](https://atoneplace.net/fastener/m12-1-75/)
- [M20×2.5](https://atoneplace.net/fastener/m20-2-5/)
- [M12×1.5](https://atoneplace.net/fastener/m12-1-5/)
- [M12×1.25](https://atoneplace.net/fastener/m12-1-25/)
- [M12×1](https://atoneplace.net/fastener/m12-1/)

## Sources

- Official vendor product documentation — At One Place (/about/)
- Typical range compiled from manufacturer specifications — At One Place (/about/)