USB-C hides different speeds, check both port and cable

Nothing in particular. USB itself stands for Universal Serial Bus, a standard launched in 1996 by a group of seven tech firms, including Microsoft, Intel, IBM and Compaq, to make it easier to plug keyboards, mice and printers into PCs. Over the years the USB family gained different connector shapes, and each one got a letter.

USB-A is the flat rectangular plug you still see on flash drives, older laptops and game consoles. USB-B is the boxier, squarish plug used on printers, some external drives and the back of many monitors. Micro USB, which was on lots of Android phones a decade ago, is a shrunken member of the B family. USB-C, officially USB Type-C, is simply the newest shape in the lineup.

Its official name is a clue in itself: Type-C means connector type C. The standard is managed by the USB Implementers Forum, a group whose members include Apple, Samsung, Intel and Microsoft.

USB-C won because it’s small, it’s reversible and it can do more. The oval plug is symmetrical, so it goes in either way up, ending the old routine of flipping a USB-A plug three times. It’s also far slimmer than USB-A or USB-B, which matters on very thin phones and laptops.

It also carries much more power and data than the older connectors, which is why it now shows up on phones, laptops, tablets, game consoles, e-readers, cameras and earbuds. Android phones switched years ago. Apple was the last big holdout and moved the iPhone from its own Lightning port to USB-C in 2023.

Every USB-C port has the same shape, but the speed depends on the protocol it supports, set by the chip inside the device. Think of the plug as a road and the protocol as the speed limit. Here are the main ones you’ll find behind a USB-C port, slowest first:

• USB 2: up to 480 Mbps (megabits per second). Fine for charging and a mouse, slow for big files.
• USB 3.2: 5 Gbps, 10 Gbps or 20 Gbps (gigabits per second), depending on the version.
• USB4 and Thunderbolt 3 or 4: up to 40 Gbps, enough for fast external drives and big monitors.
• The second version of USB4: up to 80 Gbps, for top-end storage and docking hubs.

A real example: the iPhone 17 Pro’s USB-C port supports USB 3.2 at up to 10 Gbps, while the base iPhone 17’s port is USB 2, limited to 480 Mbps. Copying a long video off the regular model takes far longer, even though the ports look exactly the same.

The cable has its own limits, and the slowest part of the chain wins. Some cheap USB-C cables carry no data at all, only power, because leaving out the data wires makes them cheaper to build. If your laptop won’t see your phone or a drive, a charge-only cable is a common reason.

Charging works the same way. The best USB-C cables handle up to 240 watts, enough for a big laptop, while the cable bundled with a pair of earbuds may top out around 20 watts. Even a 240-watt cable only charges as fast as the charger and the device allow; plug it into a 20-watt adapter and you get 20 watts. Most cables sold today are rated at 100 watts or less.

Cables that go from USB-C to the old USB-A plug are the usual bottleneck. The USB-A end caps data at 10 Gbps and standard charging at just 15 watts.

You usually can’t tell a cable’s speed by looking at it, so a few habits help:

• Look up your device’s spec sheet. Search the model name plus “USB-C speed” to see whether the port is USB 2, USB 3.2, USB4 or Thunderbolt.
• Read the cable’s rating before you buy. Look for the data speed in Gbps and the wattage. A USB4 or Thunderbolt cable has to meet stricter rules, so it’s a safer bet if your devices support it.
• Stick to known brands. Badly made cables have damaged devices and chargers. Well-known names such as Anker, Belkin, Ugreen and Apple carry less risk than no-name listings on marketplace sites.
• Check the weight in the specs. Thicker copper usually means a better signal. In one test, a $19 cable weighed 86 grams while a $9 one of the same length weighed 38 grams.
• Label your cables. Once you know which ones are fast, a strip of tape saves guesswork later.