USB 3.1 Type A and Type C: Picking the Right Pair
The rate and the connector are separate decisions. A Type-A port can run at 10 Gbps and a Type-C port can run at 480 Mbps, so knowing which connector you have tells you nothing about speed.
Quick Answer
USB 3.1 is available on both Type-A and Type-C connectors. Type-A 3.1 keeps the familiar rectangular plug and can reach 10 Gbps in the right version. Type-C adds reversibility, higher power delivery and support for 20 Gbps and alternate modes. For 10 Gbps, both the cable and the port must be rated for it, and Type-C to Type-C is the simplest way to guarantee that.
Connector Comparison
| Attribute | USB 3.1 Type-A | USB 3.1 Type-C |
|---|---|---|
| Insertion | One orientation | Reversible |
| Maximum rate | 10 Gbps | Up to 20 Gbps and beyond with USB4 |
| Power delivery | Standard 5 V charging | Up to 240 W with e-marked cables |
| Alternate modes | None | DisplayPort and more |
| Contacts | 9 | 24 |
| Typical use | Desktops, legacy devices | Laptops, phones, docks |
Common Cable Pairings
| Pairing | Maximum realistic rate | Note |
|---|---|---|
| A to C | 5 to 10 Gbps if both rated | No Power Delivery to a laptop |
| C to C | 10 to 20 Gbps | Needed for full power and speed |
| A to A 3.1 | 10 Gbps | Uncommon, used by some peripherals |
| A to B 3.1 | 10 Gbps | Taller B plug, docks and scanners |
| C to A | 5 Gbps typical | Legacy peripheral host cable |
Choosing by Situation
Desktop with Type-A ports only
Choose an A to C or A to B cable rated for the rate you need. Keep the run short for 10 Gbps.
Laptop with Type-C
Use C to C where possible. It is the only pairing that carries Power Delivery and the highest data rates.
Legacy peripheral on a modern machine
A C to A or C to B cable rated for the peripheral rate. Anything above 5 Gbps is wasted on older hardware.
Real-World Applications
- Connecting a 10 Gbps enclosure to a desktop through a Type-A 3.1 port.
- Charging and driving a dock from a single Type-C cable.
- Feeding a scanner that uses a tall B plug.
- Standardising on C to C cables across a team for clarity.
Related Guides
For generation naming, read USB 3.1 cable. For port colour conventions, see USB 3.1 colour. For hub expansion, start with 4 port USB-C hub with power delivery.
FAQ
Is USB 3.1 Type-A as fast as Type-C?
Type-A can reach 10 Gbps in its 3.1 form, but Type-C supports higher tiers and more features.
Can an A to C cable charge a laptop at 100 W?
No. Power Delivery requires USB-C at both ends with an e-marked cable.
Do I need a special cable for 10 Gbps?
Yes. The cable must be rated for 10 Gbps, not merely USB 3.1 by name.
Will a USB 3.1 cable work in a USB 2.0 port?
Yes, at 480 Mbps. The port caps the rate.