USB-C data speeds, and why a 240 W cable can still be slow
Power and data are separate ratings. Most 240 W charging cables move data at 480 Mb/s, which is USB 2.0 speed.
Every bar below can be a 240 W cable. Bandwidth is a separate rating.
Two ratings, one connector
A USB-C connector can carry anything from 480 megabits per second to 80 gigabits per second, and the wattage rating tells you nothing about which. Charging cables are built for current, not for signal integrity, so the majority of 240 W cables on the market are USB 2.0 inside: fine for a laptop, useless for an external SSD.
The tiers you will meet
The tiers you will meet are USB 2.0 at 480 Mb/s, USB 3.2 at 5, 10 or 20 Gb/s, USB4 at 40 Gb/s, and USB4 version 2 at 80 Gb/s. Only the last two guarantee the bandwidth for high-resolution displays alongside data.
Six cables, one wattage
Our cable ruler puts the power rating and the data rating side by side for exactly this reason: on our own catalogue, six cables share the same 240 W figure and range from 480 Mb/s to 80 Gb/s.
a 240 W USB4 cable does everything, at a price. Two cheaper specialised cables are often the better buy.
driving a monitor over USB-C needs DisplayPort alt mode, which is again a separate capability.
Cables we track by data speed
Full side-by-side on the cable ruler.