---
title: "M2.5×0.45 tap drill 2.05 mm, clearance 2.7 mm"
description: "M2.5×0.45: tap drill 2.05 mm, clearance hole 2.7 mm, 5 mm hex. Full thread dimensions, how to identify it, and torque."
url: https://atoneplace.net/fastener/m2-5-0-45/
site: "At One Place"
---

# M2.5×0.45 thread

**M2.5×0.45 tap drill: 2.05 mm**

Clearance hole 2.7 mm · 5 mm hex

M2.5×0.45 is a coarse metric thread with a 2.5 mm (0.098") major diameter and 0.45 mm pitch. Tap it with a 2.05 mm drill; drill 2.7 mm to pass a bolt through.

## The numbers

- **Designation:** M2.5×0.45
- **Major diameter:** 2.5 mm / 0.098"
- **Minor diameter:** 2.013 mm
- **Pitch:** 0.45 mm pitch
- **Tap drill (75% thread):** 2.05 mm — 2.05 mm
- **Clearance hole (close fit):** 2.7 mm / 0.106"
- **Hex across flats:** 5 mm

## How to measure what you have

1. Measure across the thread crests with calipers. A used M2.5×0.45 reads a little under 2.5 mm — the crests are truncated by the standard, then worn and plated, so anything from about 2.1 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 0.45 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

No torque figure is given for this size. Small and fine threads like this are generally not supplied to a strength grade, and in most assemblies the tapped material strips before the fastener yields — so a published bolt torque would be the wrong limit to work to. Tighten to snug plus a small turn, or use the figure the manufacturer of the part specifies.

## Where this size turns up

- Raspberry Pi and single-board-computer standoffs
- Laptop base-cover and hinge screws
- Servo horn and gimbal hardware

## Common questions

### What size drill for an M2.5×0.45 tap?

2.05 mm (2.05 mm), which gives about 75% thread engagement.

### What clearance hole for M2.5×0.45?

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

### What spanner fits M2.5×0.45?

5 mm across the flats on a standard hex head.

## Related pages

- [M2×0.4](https://atoneplace.net/fastener/m2-0-4/)
- [M3×0.5](https://atoneplace.net/fastener/m3-0-5/)
- [M1.6×0.35](https://atoneplace.net/fastener/m1-6-0-35/)
- [M3.5×0.6](https://atoneplace.net/fastener/m3-5-0-6/)
- [M4×0.7](https://atoneplace.net/fastener/m4-0-7/)
- [M5×0.8](https://atoneplace.net/fastener/m5-0-8/)
- [M6×1](https://atoneplace.net/fastener/m6-1/)
- [M6×0.75](https://atoneplace.net/fastener/m6-0-75/)
- [M8×1.25](https://atoneplace.net/fastener/m8-1-25/)
- [M8×1](https://atoneplace.net/fastener/m8-1/)

## Sources

- Official vendor product documentation — At One Place (/about/)