USB4 Specification Merges Thunderbolt 3 and USB With Transfer Speeds up to 40Gb/s
The USB4 specification for a new version of USB was today published by the USB Implementers Forum [PDF] giving us details on what to expect from the next-generation USB architecture following a preview back in March.
USB4 is a major update that "complements and builds upon" the current USB 3.2 2x2 (USB-C) and USB 2.0 architectures. According to the USB-IF, the USB4 architecture is based on Thunderbolt, doubling the maximum bandwidth of USB and allowing for multiple simultaneous data and display protocols.

The USB-IF outlined key specifications of the USB4 architecture, such as 40Gb/s speeds (twice the current 20Gb/s maximum) and backwards compatibility with USB 3.2 and Thunderbolt 3.
- Two-lane operation using existing USB Type-C cables and up to 40Gbps operation over 40Gbps certified cables
- Multiple data and display protocols that efficiently share the maximum aggregate bandwidth
- Backward compatibility with USB 3.2, USB 2.0 and Thunderbolt 3
USB4 will use the same USB-C connector design as USB 3, which means manufacturers will not need to introduce new USB4 ports into their devices.
Apple's newest Macs offer support for USB-C and Thunderbolt 3, which means most Mac users are already experiencing USB4 speeds when using Thunderbolt 3 cables and devices, but USB4 will make Thunderbolt-style speeds the new default and it will lower the cost of devices that use these faster transfer speeds.
USB Power Delivery will be required in devices built for USB4, which also means we can expect to see higher-powered chargers with multiple USB4 ports.
Though the USB4 specification is complete, it will still be some time before we can expect to see devices that take advantage of USB4. It typically takes at least a year for new products to come out following the finalization of a new specification, so it will be late 2020 or beyond before we begin seeing USB4 devices.
Popular Stories
Multiple rumors have suggested that the next-generation iPhone 15 models will adopt the Wi-Fi 6E standard that Apple has already introduced in the iPad Pro and MacBook Pro, and now a leaked document appears to confirm Apple's plans.
Sourced from researcher and Apple leaker Unknownz21 (@URedditor), the document features diagrams of the iPhone 15's antenna architecture. D8x refers to the...
Apple's next-generation iPhone 15 Pro and iPhone 15 Pro Max are expected to be announced in September as usual. Already, rumors suggest the devices will have at least eight exclusive features not available on the standard iPhone 15 and iPhone 15 Plus.
An overview of the eight features rumored to be exclusive to iPhone 15 Pro models:A17 chip: iPhone 15 Pro models will be equipped with an A17...
Following last week's hardware announcements, this week saw the actual release of several of the new products as well as operating system updates bringing new features and bug fixes across Apple's platforms.
This week also saw some fresh rumors about the iPhone 15 lineup and Apple's upcoming AR/VR headset, while we shared some tips to help you get the most of your macOS experience, so read...
In June 2022, Apple previewed the next generation of CarPlay, promising deeper integration with vehicle functions like A/C and FM radio, support for multiple displays across the dashboard, personalization options, and more.
Apple says the first vehicles with support for the next-generation CarPlay experience will be announced in late 2023, with committed automakers including Acura, Audi,...
New 14-inch and 16-inch MacBook Pro models with the latest M2 Pro and M2 Max chips are available in Apple retail stores and are already in the hands of customers, and we picked up one of the new M2 Max machines to answer all of the questions MacRumors readers considering a purchase might have.
Subscribe to the MacRumors YouTube channel for more videos. Yesterday, we asked MacRumors fans on...
The upcoming iPhone 15 models that are set to be introduced later in 2023 will adopt the Wi-Fi 6E standard, according to Apple analyst Ming-Chi Kuo. In a note about Apple's work on a Wi-Fi chip, Kuo said that the company will upgrade the iPhone 15 to Wi-Fi 6E.
Apple is already using Wi-Fi 6E for the 11 and 12.9-inch iPad Pro models introduced last year, along with the new Mac mini and...
The iPhone 15 will support Wi-Fi 6E, according to a research note shared this week by Barclays analysts Blayne Curtis and Tom O'Malley. The analysts did not specify whether the feature will be available on all models or limited to the Pro models.
Apple has added Wi-Fi 6E support to a handful of devices so far, including the latest 11-inch and 12.9-inch iPad Pro, 14-inch and 16-inch MacBook...
Top Rated Comments
Now lets get USB-C on an iPhone.
Inexpensive USB-C charging cables are limited to USB2 speeds and most of them are limited to 30W of power. There are 60W and higher cables, but in 6ft lengths there are not as many options and it's far from easy to figure out what you're going to get. Some suppliers write the limits in terms of watts, some in terms of volts and amps. Most laymen have trouble figuring it all out.
And then there are the chargers... 18W, 30W, 60W, 90W, 100W, 5V, 12V, 18V, 2A, 3A. Chargers with two ports get even more confusing. While it's relatively easy math, I don't think having people doing Ohm's Law calculations in their heads when buying chargers in cables is user-friendly.
But I mentioned basic charging cables are super slow for data. If you want to use a USB-C cable for data, then it's even more confusing. Speeds vary depending on cable length and spec variant compatibility - a USB-C Gen 1 vs USB-C Gen 2 vs Thunderbolt 3; 1.5ft vs 3ft vs 6ft. Each combination will have a different max speed. It's all very difficult for most folks to keep straight.
Basically, USB is still a spaghetti of specs and limits, and this is just adding yet another layer. Just because the physical plug of Type C is nice, does not mean all the other USB problems are solved.
I know this is controversial but I'd much rather keep a robust port on the iPhone (lightning) than a convenient yet fragile one (USB C).