---
title: "M5×0.8 tap drill 4.2 mm, clearance 5.3 mm"
description: "M5×0.8: tap drill 4.2 mm, clearance hole 5.3 mm, 8 mm hex. Full thread dimensions, how to identify it, and torque."
url: https://atoneplace.net/fastener/m5-0-8/
site: "At One Place"
---

# M5×0.8 thread

**M5×0.8 tap drill: 4.2 mm**

Clearance hole 5.3 mm · 8 mm hex

M5×0.8 is a coarse metric thread with a 5 mm (0.197") major diameter and 0.8 mm pitch. Tap it with a 4.2 mm drill; drill 5.3 mm to pass a bolt through.

## The numbers

- **Designation:** M5×0.8
- **Major diameter:** 5 mm / 0.197"
- **Minor diameter:** 4.134 mm
- **Pitch:** 0.8 mm pitch
- **Tap drill (75% thread):** 4.2 mm — 4.2 mm
- **Clearance hole (close fit):** 5.3 mm / 0.209"
- **Hex across flats:** 8 mm

## How to measure what you have

1. Measure across the thread crests with calipers. A used M5×0.8 reads a little under 5 mm — the crests are truncated by the standard, then worn and plated, so anything from about 4.6 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 0.8 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: 5–6.8 N·m**

3.7–5.0 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

- Bicycle bottle cage bosses
- Bicycle disc rotor bolts and stem face-plate bolts
- T-slot nuts in 2020 aluminium extrusion
- VESA 200×200 monitor and TV mounts

## Common questions

### What size drill for an M5×0.8 tap?

4.2 mm (4.2 mm), which gives about 75% thread engagement.

### What clearance hole for M5×0.8?

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

### What spanner fits M5×0.8?

8 mm across the flats on a standard hex head.

## Related pages

- [M4×0.7](https://atoneplace.net/fastener/m4-0-7/)
- [M6×1](https://atoneplace.net/fastener/m6-1/)
- [M6×0.75](https://atoneplace.net/fastener/m6-0-75/)
- [M3.5×0.6](https://atoneplace.net/fastener/m3-5-0-6/)
- [M3×0.5](https://atoneplace.net/fastener/m3-0-5/)
- [M2.5×0.45](https://atoneplace.net/fastener/m2-5-0-45/)
- [M2×0.4](https://atoneplace.net/fastener/m2-0-4/)
- [M8×1.25](https://atoneplace.net/fastener/m8-1-25/)
- [M8×1](https://atoneplace.net/fastener/m8-1/)
- [M8×0.75](https://atoneplace.net/fastener/m8-0-75/)

## Sources

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