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.

usbccable
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

MacRumors x Bloomberg Banner Cool

Apple Reportedly Plans to Unveil at Least Five New Products Next Week

Sunday February 22, 2026 9:48 am PST by
In his Power On newsletter today, Bloomberg's Mark Gurman said Apple will have a three-day stretch of product announcements from Monday, March 2 through Wednesday, March 4. In total, he expects Apple to introduce "at least five products." Subscribe to the MacRumors YouTube channel for more videos. A week ago, Apple invited selected journalists and content creators to an "Apple Experience" in...
maxresdefault

iPhone Fold: Launch, Pricing, and What to Expect From Apple's Foldable

Friday February 20, 2026 3:21 am PST by
Apple is expected to launch a new foldable iPhone this year, based on multiple rumors and credible sources. The long-awaited device has been rumored for years now, but signs increasingly suggest that Apple will release its first foldable device in 2026. Subscribe to the MacRumors YouTube channel for more videos. Below, we've collated an updated set of key details that have been leaked about ...
iOS 26

iOS 26.3.1 Update for iPhones Coming Soon as 'Apple Experience' Nears

Sunday February 22, 2026 5:29 pm PST by
Apple's software engineers are testing iOS 26.3.1, according to the MacRumors visitor logs, which have been a reliable indicator of upcoming iOS versions. iOS 26.3.1 should be a minor update that fixes bugs and/or security vulnerabilities, and it will likely be released within the next two weeks. Last month, Apple released iOS 26.2.1 with bug fixes and support for the second-generation...
iPhone 18 Pro Deep Red Feature

Apple is Testing These iPhone 18 Pro and Foldable iPhone Colors

Sunday February 22, 2026 8:41 am PST by
The special new color that Apple is considering for the iPhone 18 Pro and iPhone 18 Pro Max this year is red, according to Bloomberg's Mark Gurman. Specifically, he said that Apple is testing a "deep red" finish for the two devices. If this rumor materializes, it would be the first time that the Pro and Pro Max models ever come in red, and the iPhone 18 Pro models would be the first...
Low Cost A18 Pro MacBook Feature Pink

Apple's Low-Cost Colorful MacBook: All the Rumors

Friday February 20, 2026 2:37 pm PST by
Apple has been developing a more affordable version of the MacBook, and it's rumored to be launching in under two weeks. This is going to be one of Apple's most unique Macs, because there hasn't really been anything quite like it before. We've rounded up everything we know about the low-cost MacBook ahead of its March debut. Design Rumors about the MacBook's design make it sound a lot...

Top Rated Comments

85 months ago
One cable to rule them all.

Now lets get USB-C on an iPhone.
Score: 49 Votes (Like | Disagree)
oneMadRssn Avatar
85 months ago
One cable to rule them all.

Now lets get USB-C on an iPhone.
Don't get me wrong, I like USB-C, but it is not the panacea everyone makes it out to be. There is not "one cable." There are a large number of different USB-C cables, all with different specs, speeds, etc.

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.
Score: 33 Votes (Like | Disagree)
Internet Enzyme Avatar
85 months ago
Congratulations Apple, you were four or five years early—you certainly earn that distinction. Too bad that the products in the meantime were entirely unflexible and annoying for anyone who wanted to conveniently use their laptop as a computer
Score: 16 Votes (Like | Disagree)
Spock Avatar
85 months ago
I don’t even have a Mac with USBC yet..
Score: 12 Votes (Like | Disagree)
tofagerl Avatar
85 months ago
Will USB4 then drop support for USB-A, B and B's little cousins mini and micro? Because if so, it's about time!
Score: 10 Votes (Like | Disagree)
zakarhino Avatar
85 months ago
Lightning is still the most robust port design I've ever come across for serious charging/data capabilities. I can plug my phone in every day multiple times a day for two years and the port will still be solid enough to dangle the iPhone from its charging cable no problem. Meanwhile the USB C ports on my MacBook are stupidly loose after just a couple months of use to the point where occasionally the charger would unplug itself if you move the laptop in a strange way.

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).
Score: 7 Votes (Like | Disagree)