USB4® is the fifth major revision of the Universal Serial Bus (USB) standard. USB4 builds on the flexibility of USB‑C while dramatically improving speed, video support, and power delivery. This knowledge base explains USB4 in simple terms: what it is, how it works, and what you should expect when using it.
USB4 is a modern USB standard designed to carry data, video, and power simultaneously over a single USB-C cable. It introduces a new internal system called USB4 Fabric, which packages different types of signals and routes them efficiently, similar to how data moves through a network.
USB4 supports speeds of up to 80 Gbps and remains backward-compatible with older USB versions.
| Feature | USB4 Capability |
|---|---|
| Maximum Speed | Up to 40 - 80 Gbps |
| Minimum Required Speed | 20 Gbps |
| Connector Type | USB-C only |
| Video Support | DisplayPort tunneling |
| Power Delivery | 240W Power Delivery (USB‑PD) |
| Backward Compatibility | USB 3.0/3.1/3.2, USB 2.0, USB 1.1 |
USB4 currently supports three main speed levels to date:
| USB4 Mode | Maximum Speed | Cable Requirement |
|---|---|---|
| USB4 Gen 2×2 | 20 Gbps | Standard USB‑C cable |
| USB4 Gen 3×2 | 40 Gbps | USB4 / Thunderbolt‑rated cable |
| USB4 v2 / USB 80 Gbps | 80 Gbps | USB4 / Thunderbolt‑rated cable |
To reach the full 80 Gbps, certified high‑quality cables are required. All USB4 devices must support at least 20 Gbps.
The official name is USB4, not “USB 4.” This was intentional. The USB standards organization wants USB4 to function as a long‑term platform name, with future improvements labeled using suffixes (such as 2×2 and 3×2) rather than entirely new names.
| Original Name | Updated Name | Current Name | Max Speed | Connector |
|---|---|---|---|---|
| USB 3.0 | USB 3.1 Gen 1 | USB 3.2 Gen 1 | 5 Gbps | USB‑A / USB-C |
| USB 3.1 | USB 3.1 Gen 2 | USB 3.2 Gen 2 | 10 Gbps | USB‑A / USB-C |
| USB 3.2 | — | USB 3.2 Gen 2×2 | 20 Gbps | USB-C |
| — | — | USB4 Gen 2×2 | 20 Gbps | USB-C |
| — | — | USB4 Gen 3×2 | 40 Gbps | USB-C |
| — | — | USB4 v2 / USB 80 Gbps | 80 Gbps | USB-C |
USB4 delivers a major leap in performance compared to previous USB standards, enabling higher data throughput, improved display support, and more efficient handling of multiple data streams.
Not every USB4 device supports every optional feature, but certain capabilities are required.
USB4 Host Devices Must Support:
USB4 Hubs Must Support:
USB4 requires USB-C connectors for all devices and cables.
Achieving full 40Gbps or 80Gbps performance requires short, high-quality certified cables.
USB4 supports up to 240W of power, enabling charging for laptops, displays, and accessories.
Cable Length Guidelines:
| Speed | Max Cable Length |
|---|---|
| 80 Gbps | ~0.4 m (1.6 ft) |
| 40 Gbps | ~0.8 m (2.6 ft) |
| 20 Gbps | ~2 m (6.5 ft) |
Longer cables may work but can reduce performance unless they are active or optical cables.
No, but they are closely related.
USB4 is based on Thunderbolt 3 technology, but Thunderbolt remains a separate standard. Some USB4 devices may include Thunderbolt support, but this is optional and manufacturer‑dependent.
USB4 supports DisplayPort 2.1 functionality, allowing high‑resolution and high‑refresh‑rate video. Actual performance depends on the device and cable used.
USB4 is backwards compatible with previous USB versions such as:
USB4 simplifies connectivity while preparing systems for higher performance needs now and in the future.
