---
title: "USB4 size — 20, 40 or 80 Gbit/s; USB-C connector only"
description: "USB4: 40 Gbit/s typical, built on the Thunderbolt 3 protocol. Full dimensions in millimetres, centimetres and inches, and what the standard actually specifies."
url: https://atoneplace.net/size/usb-4/
site: "At One Place"
---

# USB4 size

**USB4: 20, 40 or 80 Gbit/s; USB-C connector only**

USB4 is USB-C only and is based on Thunderbolt 3, which Intel contributed to the specification. It supports tunnelling DisplayPort and PCIe over the same cable, which is what allows a single connector to carry video, data and power. Written without a space — USB4, not USB 4 — which is the official styling. USB4 Version 2.0 adds an 80 Gbit/s mode.

## The numbers

- **Specification:** 20, 40 or 80 Gbit/s; USB-C connector only
- **Defined by:** USB-IF

## USB

| Size | Millimetres | Inches |
| --- | --- | --- |
| USB-C connector | 8.34 × 2.56 mm | 0.33 × 0.10 |
| USB4 ← | 20, 40 or 80 Gbit/s; USB-C connector only | — |
| USB 3.x | 5, 10 or 20 Gbit/s depending on generation | — |
| USB 2.0 | 480 Mbit/s, 2.5 W (500 mA at 5 V) | — |

## Common questions

### What size is USB4?

40 Gbit/s typical, built on the Thunderbolt 3 protocol.

### Which standard defines USB4?

USB-IF

## Related pages

- [USB-C connector size](https://atoneplace.net/size/usb-c/)
- [USB 3.x size](https://atoneplace.net/size/usb-3/)
- [USB 2.0 size](https://atoneplace.net/size/usb-2/)

## Sources

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