Understanding the USB Naming Scheme

Universal Serial Bus (USB) is one of the most widely used standards for connecting devices to computers and other electronics. Over the years, USB technology has evolved, offering faster data transfer speeds and increased functionality. However, the naming conventions for USB versions have been a source of confusion, as they have changed multiple times. In this article, we’ll explore the history of USB naming, how it evolved, and what each version means in terms of capabilities.

Early Days: USB 1.0 and 1.1

The USB standard was introduced in 1996 to simplify connections between computers and peripherals, replacing older interfaces like serial and parallel ports. The first version, USB 1.0, supported data transfer speeds of 1.5 Mbps (low-speed) and 12 Mbps (full-speed), making it suitable for keyboards, mice, and printers. However, USB 1.0 wasn’t widely adopted due to its limitations and the need for improvements in reliability.

In 1998, USB 1.1 was released, fixing compatibility issues and improving performance. This version became widely adopted and established USB as the standard connector for many peripherals. The naming was straightforward, as there were only two versions and one speed class.

The Era of High-Speed: USB 2.0

In 2000, USB 2.0 was introduced with a significant leap in data transfer speed, going up to 480 Mbps (High-Speed). USB 2.0 maintained backward compatibility with USB 1.1, meaning it could work with older devices and ports but at the speed of the lowest version (USB 1.1 speed when used with a USB 1.1 port or device).

The straightforward naming scheme USB 1.1 and USB 2.0 made it easy for consumers to understand, as there was a clear progression in speeds and capabilities.

The Introduction of SuperSpeed: USB 3.0 and the Beginning of Confusion

In 2008, the USB 3.0 specification was released, introducing SuperSpeed with data transfer rates up to 5 Gbps. This was a substantial improvement, making USB suitable for high-speed storage devices and other data intensive applications.

The naming was still straightforward at this point, with USB 3.0 standing on its own as the high-speed option alongside USB 2.0.

Rebranding Confusion: USB 3.1 and USB 3.1 Gen 1 / Gen 2

In 2013, the USB 3.1 specification was released, raising data transfer speeds to 10 Gbps. This speed was marketed as SuperSpeed+. However, this is when the USB naming convention started to become confusing:

  • USB 3.0 was rebranded as USB 3.1 Gen 1 (5 Gbps).

  • The new, faster 10 Gbps version was named USB 3.1 Gen 2

This rebranding caused confusion because devices that previously supported USB 3.0 were now labelled as USB 3.1 Gen 1, despite having the same 5 Gbps speed. The terms Gen 1 and Gen 2 were added to differentiate the speeds, but this was not immediately clear to many consumers, who were left wondering why USB 3.1 had two different speed ratings.

Further Complication: USB 3.2 and the “Gen” System

In 2017, the USB 3.2 specification was released, increasing data transfer speeds to 20 Gbps. To achieve this speed, USB 3.2 introduced a dual-lane technology, allowing two 10 Gbps lanes to operate simultaneously. However, this release added yet another layer of complexity to the naming scheme, as the USB-IF (USB Implementers Forum) decided to rebrand all previous USB 3.x versions again:

  • USB 3.1 Gen 1 (5 Gbps) became USB 3.2 Gen 1 x 1.

  • USB 3.1 Gen 2 (10 Gbps) became USB 3.2 Gen 2 x 1.

  • The new USB 3.2 (20 Gbps) became USB 3.2 Gen 2 x 2.

The “Gen” and “x 1” / “x 2” terminology indicates the speed and the number of lanes, respectively, but this naming scheme has made it difficult for consumers to know what kind of performance to expect just by looking at the USB version number.

USB4: A Simplified Future?

In 2019, USB4 was announced, promising data transfer speeds of up to 40 Gbps. USB4 is based on Thunderbolt 3 technology, allowing compatibility with Thunderbolt devices and USB-C. Unlike the USB 3.x naming scheme, USB4 aims to simplify things by consolidating its features:

  • USB4 20 Gbps: A 20 Gbps version.

  • USB4 40 Gbps: A 40 Gbps version

The USB-IF decided not to include “Gen” or “x” terminology with USB4, making it more straightforward for consumers. Additionally, USB4 mandates the use of USB-C connectors, eliminating the traditional Type-A connector, which further simplifies compatibility.

USB4 is backward compatible with USB 3.x and USB 2.0, meaning it will work with existing devices but at the speed of the older standard when used with those devices.

Understanding USB Logos and Branding

To help consumers identify USB speeds, the USB-IF introduced new logos that manufacturers can use on packaging, devices, and cables. These logos display the speed directly, like “USB 5 Gbps” or “USB 10 Gbps,” without requiring consumers to decipher version numbers and generation names. These logos help reduce confusion, especially for USB-C cables and ports, which otherwise look identical but can support vastly different speeds.

Naming Summary

This table provides a comprehensive summary of the USB naming conventions, highlighting the evolution from each original USB version to its latest branded name. It includes previous names where rebranding has occurred, along with the associated data transfer speeds and the year each version was introduced. This summary helps clarify the progression and renaming of USB standards for better understanding of current terminology and capabilities.

Original Name Previous Names Current (Latest) Branded Name Data Transfer Speed Introduced Year
USB 1.0   USB 1.0 1.5 Mbps (Low Speed) 1996
USB 1.1   USB 1.1 12 Mbps (Full Speed) 1998
USB 2.0   USB 2.0 480 Mbps (High Speed) 2000
USB 3.0
  • USB 3.1 Gen 1
  • USB 3.2 Gen 1
 USB 5 Gbps 5 Gbps (SuperSpeed) 2008
USB 3.1
  • USB 3.1 Gen 2
  • USB 3.2 Gen 2
 USB 10 Gbps 10 Gbps (SuperSpeed) 2013
USB 3.2
  • USB 3.2 Gen 2x2
 USB 3.2 Gen 2 x 2 20 Gbps (SuperSpeed++) 2017
USB4 20 Gbps   USB4 20 Gbps 20 Gbps 2019
USB4 40 Gbps   USB4 40 Gbps 40 Gbps 2019
USB4 80 Gbps   USB4 80 Gbps 80 Gbps 2024