The ubiquity of the USB-C connection has brought many benefits, but it has also caused some confusion. This is particularly true when it comes to Thunderbolt 3. Many modern laptops boast USB-C ports, but only some of these support Thunderbolt 3 (TB3). Laptops that boast TB3 often come at a price premium over those with only USB-C. So which one is the best option for you?
We at Cable Matters hope to burn away the fog surrounding USB-C vs. Thunderbolt 3 so you can make an informed decision as to whether USB-C will be enough or if you need the additional features of a TB3 connection.
What exactly is USB-C?
USB-C (formally known as USB Type-C) and Thunderbolt 3 describe different things. USB-C is, by itself, just a form-factor for a connection. Think of USB-C as an evolution of the design of older boxy USB connectors (known as Type-A). USB-C is a reversible connector, which means no more fiddling when plugging it in. It also has more pins than USB-A, allowing for increased power delivery, data transfer speeds, and video bandwidth to travel across the cable.
In general, when the term “USB-C” is used in the product description, it should be seen as shorthand for “a USB port that uses the Type-C form factor.” Many tech outlets and retailers have muddied the waters by using the term “USB-C” to refer to both the transfer specifications and the form factor. For comparison's sake, the term "USB-C" will refer to both the USB Type-C form factor and USB 3.2 data specification concurrently throughout the rest of the article. More information about USB-C and the USB 3.2 specification can be found here. Thunderbolt 3, by contrast, refers to specifications detailing transfer speeds, data bandwidth, and more. The take-home message is to remember that TB3 uses a USB-C connector but offers additional features over the vanilla USB protocol.
The USB Type-C connection (left) features a different design than the older USB Type-A connection type (right).
Similarities between USB-C and Thunderbolt 3
When discussing USB-C vs. Thunderbolt 3, it’s important to note that both connections share quite a bit in common. Both use the Type-C form factor for the connection. Both USB-C and TB3 can be used to power devices, transfer data at high speeds, and connect a variety of peripherals including displays. Both can be used to connect a computer to a compatible docking station, which you may want to use.
Differences between USB-C and Thunderbolt 3
While USB-C and TB3 offer similar general functionality, there are noticeable differences between the two standards. The key differences between USB-C and TB3 can be boiled down to three main points: data transfer rates, display connections, and connecting external devices.
- Data transfer: Thunderbolt 3 is significantly faster than USB-C. USB-C supports transfer speeds ranging from 480 Mbps (USB 2.0) to 20 Gbps (USB 3.2 Gen 2x2); 10 Gbps is the most common speed. Thunderbolt 3 supports transfer rates up to 40 Gbps. In general, a laptop with Thunderbolt 3 can transfer data over that port to another device 2-4 times faster than a laptop with USB-C. The attached device must support those speeds (e.g., a Thunderbolt 3 external hard drive).
- Display connections: One of the big draws of Thunderbolt 3 is its versatility. In addition to offering blazingly fast transfer speeds, Thunderbolt 3 has the bandwidth to drive up to two 4K monitors at 60 Hz. USB-C can also support external displays with the optional “DisplayPort Alternate Mode” feature. Without this feature, displays will not work when connected via USB-C. Verify that your computer supports this feature if you intend to use an external display over USB-C.
- Device support: USB-C and TB3 can both be used to connect a variety of peripherals such as printers and hard drives. TB3, however, supports PCIe devices like external GPUs and fast external hard drives. USB-C simply cannot connect to these kinds of devices.
- Daisy-chaining: TB3 supports daisy-chaining. Up to 6 compatible devices can be connected in a chain using their own TB3 ports instead of connecting to the host device. With USB-C, these devices would all need to connect to individual host USB-C ports.
- Backward compatibility: TB3 is compatible with USB-C. If a USB-C device is plugged into a TB3 port, the port reverts to USB-C mode to support the device. Compatibility is not reciprocal, however. A USB-C only port will not work with a Thunderbolt 3 device. Thunderbolt 3 docking stations such as the one below require a Thunderbolt 3 host.
If you need fast transfer speeds, support for multiple 4K 60Hz displays, or an external GPU, look for the Thunderbolt 3 lightning bolt symbol. (Buy the Aluminum Thunderbolt 3 dock here.)
Do you need Thunderbolt 3, or is USB-C enough?
The decision between USB-C and Thunderbolt 3 comes down to your personal usage. You should consider these three points before making a purchase:
- Are my file transfers time-sensitive? Most laptops with USB-C can transfer a full-length HD movie in 30 seconds or fewer. If you’re not regularly transferring large data sets on a deadline from an external device that benefits from the increased speeds, you likely won’t benefit from TB3’s 40Gbps transfer speeds
- Do I need to use two 4K 60Hz monitors? If the answer is no, then USB-C (or an HDMI or DisplayPort) connection should be perfectly fine for connecting a monitor. USB-C will power two 4K 30Hz monitors, but you’ll need Thunderbolt 3 to bump that up to 60Hz.
- Do I want an external GPU for gaming or rendering work? You will need a computer with Thunderbolt 3 to be able to connect an eGPU (at least until USB4 comes out). If you don’t need or want an external GPU, USB-C is perfectly fine.
USB-C vs. Thunderbolt 3: Final Points
In general, USB-C will meet the needs of most people. However, there are specific use cases where Thunderbolt 3 is advantageous (or even necessary). Faster data transfer speeds (40 Gbps vs. 10-20 Gbps), support for two high-resolution displays, and the ability to connect devices like external GPUs are only available via Thunderbolt 3.
Keep in mind that Thunderbolt 3 is a proprietary connection, the copyright of which is owned by Intel. As such, Thunderbolt 3 often comes at a price over USB-C. If work doesn’t demand data-hungry peripherals, USB-C is a flexible and cost-effective option for most users.