USB-C Data Transfer Speeds: From USB 2.0 to Thunderbolt 4

On Sep 26, 2023

USB-C, also known as USB Type-C, represents the future of wired connectivity. With its distinctive reversible connector, support for diverse technologies, and advanced features, USB-C aspires to become a versatile universal connector.

However, as the importance of rapid data transfer continues to grow, the question arises: How fast can USB-C truly perform?

The official USB-C specification, finalized in August 2014, introduced a 24-pin reversible connector, which can be inserted into the port in any orientation. USB-C’s design enables it to provide more power compared to its predecessors, all while seamlessly coexisting with various connectors such as USB-A, USB-B, HDMI, DisplayPort, and the 3.5mm audio jack.

It’s crucial to note that USB-C refers solely to the connector’s physical style, not the specific USB protocol it supports. Consequently, this versatile connector accommodates USB 2.0, USB 3.1 Gen 1 (USB 3.0), USB 3.1 Gen 2, USB 3.2 (and its subsequent iterations), USB4, and even Thunderbolt 3 and 4. USB-C connectors are only marginally larger than micro-USB connectors, offering a thin yet robust connection suitable for both mobile devices and power-hungry laptops.

Although the USB-C connector itself lacks backward compatibility with USB-A ports, you can utilize adapters to connect USB-C devices to older USB ports. However, the connectivity will be limited to the capabilities of the USB-A or USB-B port.

USB-C Data Transfer Standards: As previously mentioned, USB-C supports various protocols, each with distinct data transfer speeds, ranging from 480Mbps to 40Gbps. While higher speeds are theoretically possible, they have yet to be fully realized. It’s important to recognize that two USB-C cables that appear identical may deliver significantly different data transfer rates.

USB 1.x: The initial USB standard provided data transfer rates of 1.5 megabits per second (Mbps) at low speed and 12 Mbps at full speed. USB 1.x played a pivotal role in eliminating legacy ports, such as serial and PS/2 ports, from computers, resulting in more compact and portable devices. Today, USB-C cables generally support a minimum of USB 2.0, while retaining backward compatibility with USB 1.0.
USB 2.0: Introduced in 2000, USB 2.0 enhanced the previous standard, elevating the maximum data transfer speed to 480 Mbps.
USB 3.x: The third generation of USB introduced significant speed improvements. USB 3.2 Gen 2×2 employs multi-lane signaling to achieve data transfer speeds of up to 20Gbps.
USB4: Conforming to Thunderbolt 3 specifications, USB4 can tunnel various protocols, including PCIe and DisplayPort. USB4 can achieve substantially higher speeds than USB 3.2, even with existing cables. The USB4 V2.0 specification further increased theoretical transfer speeds to 80Gbps in bidirectional mode and 120Gbps in asymmetric mode.
Thunderbolt 3: Intel’s once-proprietary standard, now royalty-free, also utilizes a USB-C connector and supports data transfer speeds of up to 40Gbps.
Thunderbolt 4: Thunderbolt 4 shares the same theoretical maximum transfer speed as USB4 and Thunderbolt 3 but enhances the PCIe data requirement to 32Gbps from 16Gbps, with additional distinctions compared to USB4.

What is the maximum theoretical data transfer limit for USB-C? The USB-C connector is capable of achieving remarkably high data transfer speeds. USB4 is anticipated to reach speeds of 80Gbps and 120Gbps, although products supporting these levels are not yet available. Furthermore, future iterations like Thunderbolt 5 are likely to offer similar speeds.

Currently, the highest attainable data transfer speed through a USB-C connection is 40Gbps, available on select Apple, Intel, and AMD laptops released after 2020. However, it’s essential to understand that these speeds are purely theoretical and are likely to vary significantly in real-world usage. Factors affecting USB transfer speeds include cable length, cable quality, device compatibility (a USB 2.0 to USB 3.2 connection operates at USB 2.0 speeds), interference, and the type of files being transferred. The speed of the drive being used also plays a role, with modern PCIe SSDs offering much faster data transfers than older hard drives, regardless of the USB standard in use. There are various methods to enhance USB data transfer speed on Windows, which can be beneficial when encountering sluggish transfer rates.