USB-C to USB-C Cables: Charging, Data and Video Explained
A USB-C cable that charges your laptop can still be the wrong cable for your screen or external drive. The plugs look the same; what you can do with them depends on the cable’s capabilities.
Think about what you need it to do: charging, moving files or connecting a display. Each has its own specification; one impressive number does not cover all three.
Begin with charging
For charging a phone or laptop, start with the power rating. Watts are volts multiplied by amps, so both the cable’s current and voltage ratings matter.
USB Power Delivery (PD) lets the charger and device agree on power within the cable’s limits. A 240W cable cannot make a lower-power charger deliver 240W. [4]
| Cable rating | Maximum PD example | Check |
|---|---|---|
| 60W | 20V × 3A | 3A cable. |
| 100W | 20V × 5A | 5A e-marked cable; not an EPR rating. |
| 240W | 48V × 5A | 5A EPR cable with electronic marking. |
Above 100W, all three parts need Extended Power Range (EPR) support, including for 28V/140W, 36V/180W and 48V/240W charging. [4]
This is where the e-marker comes in: a small chip that tells the connected equipment what the cable supports. It is required in 5A and full-featured USB-C cables, while a 3A USB 2.0 cable can omit it. EPR cables must identify their EPR capability. Having the chip does not, by itself, promise fast data, video or 240W charging. [6]
USB-IF’s current cable certification uses 60W and 240W power markings. New 100W cable certification ended in 2021. [5]
When you want to move files, look at speed
A cable can support high-power charging and still transfer data at USB 2.0 speeds. So when you connect an external drive, look for the separate Mbps or Gbps rating. “Charge-only” or “no data” means no file transfer; USB 2.0 does transfer files, at up to 480Mbps. [2]
| Specification | What it means |
|---|---|
| No data / charge-only | No file transfer; no monitor video. |
| USB 2.0 | Up to 480Mbps; data support, but no DisplayPort Alt Mode. |
| USB 5Gbps / 10Gbps | USB 3.2 Gen 1 / Gen 2 respectively. |
| USB 20Gbps | Can refer to USB 3.2 Gen 2x2 or USB4; check the protocol. |
| USB 40Gbps | A USB4 performance level. |
| USB 80Gbps | A performance level enabled by USB4 Version 2.0. |
These are signalling speeds, rather than guaranteed file-copy speeds. The computer and connected device must support the intended connection too. [1] [3]
For docks and drives, the protocol matters too. USB4 and Thunderbolt share USB-C connectors but have different feature and certification requirements. USB4 supports earlier USB connections at mutually supported capabilities; a Thunderbolt accessory needs explicit compatibility with its generation. [3] [8]
Thunderbolt 4 provides 40Gbps; Thunderbolt 5 provides 80Gbps in each direction. Its up-to-120Gbps Bandwidth Boost increases capacity in one direction for demanding display traffic, rather than guaranteeing that speed for file copies. [8]
Adding a screen brings one more check
Once video is part of the setup, charging watts and USB speed no longer tell the whole story. A direct USB-C monitor connection using DisplayPort Alt Mode needs a compatible computer port, cable and monitor input. USB4 and Thunderbolt can also carry DisplayPort video. [7] [3]
Look for a complete display mode, such as 4K at 60Hz, 4K at 120Hz or 8K at 60Hz. Refresh rate, colour settings and any required Display Stream Compression (DSC) must work across the whole setup. A bare “8K” label leaves part of that story untold. [7]
What about the wires inside?
Terms such as twisted pair, micro-coax and twinax describe the signal wires inside. The USB Type-C specification allows all three constructions for high-speed wires; none is a speed grade on its own. [6]
The cable’s stated capabilities at your chosen length remain the useful guide. Active cables add signal electronics, so check their supported modes as well.
Cruxtec offers a range of quality USB-C to USB-C cables with different specifications for charging, data and display connections. Explore Cruxtec USB cables and compare each model’s power, data speed, video support and length with the equipment you want to connect.
References
- USB-IF: USB data performance naming; USB 3.2 speed levels.
- USB-IF: USB-C and USB 2.0 cable capabilities.
- USB-IF: USB4 performance and compatibility.
- USB-IF: USB Power Delivery.
- USB-IF: Cable power markings; 100W certification update.
- USB-IF: USB Type-C specification, Release 2.5 (Table 3-1; Sections 3.3.1, 3.4.1.1, 3.4.2.1, 3.11.2; Chapter 6).
- VESA: DisplayPort and video over USB-C FAQ.
- Intel: Thunderbolt technology and generation comparison.
USB4, USB Type-C and USB-C are trademarks of USB Implementers Forum. DisplayPort is a trademark of the Video Electronics Standards Association. Thunderbolt is a trademark of Intel Corporation or its subsidiaries.
