USB 3 vs Thunderbolt: which cable should you use?
The external port decision that shapes how fast you can back up.
Thunderbolt 4 (and its twin, USB 4) runs at 40 Gbps, 8× the speed of USB 3.0's 5 Gbps and 4× that of USB 3.2 Gen 2's 10 Gbps. For bulk data transfer and external SSDs that advantage is immediate and obvious: 1 TB copies in about 3.5 minutes on Thunderbolt vs 27 minutes on USB 3.0. Thunderbolt also does things USB 3 can't do natively: daisy-chain up to 6 devices, pass a 4K 60 Hz display signal alongside data, and deliver up to 100 W of power.
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Time to move 1 TB
Backing up a 1 TB external SSD at each interface's peak link rate. This is the gap you feel every time you copy a large folder: a coffee break on USB 3.0 versus a few minutes on Thunderbolt 4.
Thunderbolt 4 (40 Gbps) is 8.0× faster for this transfer.
5 Gbps sustained
40 Gbps sustained
Assumes the link is the bottleneck at the labeled speed. Real copies are also bounded by the slower drive at each end.
Try another file size? Open the Data Transfer Calculator
Side-by-side specs
| Spec | USB 3 (3.0 / 3.2 Gen 1) | Thunderbolt 4 / USB 4 |
|---|---|---|
| Max data rate | 5-20 Gbps (versions) | 40 Gbps (TB4/USB4) / 80 Gbps (TB5) (better on this spec) |
| 1 TB transfer time (peak) | 26m 40s (USB 3.0) | 3m 20s (TB4) (better on this spec) |
| Connector | USB-A or USB-C | USB-C only |
| Display support | Alt Mode (limited) | Full DisplayPort 1.4/2.1 tunnel (better on this spec) |
| Max displays | 1 (sometimes) | 2 at 4K 60 Hz (TB4) (better on this spec) |
| Power delivery | Up to 100 W (USB-C PD) | Up to 100 W (minimum) |
| Daisy-chain | No | Up to 6 devices (better on this spec) |
| PCIe tunneling (eGPU) | No | PCIe 4.0 x4 (better on this spec) |
| Typical cable price (1 m) | $5-15 (better on this spec) | $30-70 |
| Backwards compatible | Both ways with older USB | Accepts USB 3 devices |
| Found on budget laptops | Always (better on this spec) | Rarely |
How they differ
USB 3.2 Gen 2 (10 Gbps) and USB 3.2 Gen 2×2 (20 Gbps) narrow the raw-speed gap, but Thunderbolt keeps its feature advantage in display and PCIe tunneling. On a MacBook, Thunderbolt lets you daisy-chain a 4K monitor, an external GPU enclosure, and a fast SSD to the same port, and no USB 3 variant supports the full PCIe tunnel and DisplayPort Alt Mode combination Thunderbolt uses. Physical connectors are identical, both use USB-C, so compatibility is a matter of what silicon sits behind the port. A Thunderbolt port always accepts USB 3 devices (and cables) at reduced speed. A USB 3 port doesn't accept Thunderbolt devices at all.
Verdict
For a single external SSD or hub, USB 3.2 Gen 2 (10 Gbps) is enough and widely supported. For anything involving large transfer workflows (video editing, backups, eGPU enclosures, chained displays), Thunderbolt 4 is the only answer. If your laptop has both, use Thunderbolt unless you explicitly need a USB 3-only device.
See 1 TB over Thunderbolt 4Which should you pick?
Choose USB 3 (3.0 / 3.2 Gen 1)
Pick USB 3 for general peripherals, single external drives, keyboards, webcams, and any device where 5-10 Gbps is comfortably more than the bottleneck. It's cheaper and universal.
See a 100 GB transfer over USB 3Choose Thunderbolt 4 / USB 4
Pick Thunderbolt 4 / USB 4 for external SSDs over 1 TB used regularly, for daisy-chained displays, eGPUs, docking stations driving multiple 4K monitors, or high-bandwidth audio/video capture.
See 1 TB over Thunderbolt 4Related comparisons
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