I tested 10 USB-C cables with a $45 tester, and a third of them were lying about what they could do

When USB-C was first unveiled, it came with some lofty expectations. People hoped it would finally be the universal cable we were always promised. Truly reversible and able to handle high-speed data and power at various lengths. But what we got was quite different. Now, all USB-C cables looking the same means we're left with mismatched standards and hidden specs, and it's impossible to tell one cable from another.

Looking at a USB-C cable tells you almost nothing about what it can actually do. High-speed USB4 cables look identical to old USB 2.0 cables, and vice versa, and the power situation is no different. Thankfully, there are tools to help, and one is a handy cable tester that you can buy for around $45.

The myth of the universal cable

Identical USB-C plugs hide different capabilities

Take a look at the cables in the images above. They all look the same, right? That's kind of the point: a universal standard for cables means that all cables will be universal. In that sense, they can all be plugged into the same ports and work to some extent. But the extent to which they work varies wildly from one cable to another, and that's a problem.

From the outside, one USB-C cable looks like the next. But on the inside, they can be completely different. The number of pins that are actually connected can vary, as can the thickness of the copper wire beneath that rubber or braided shielding. Some cables have special chips inside that can tell devices what they are capable of. It's that chip that tells your laptop to ask for the full wattage when charging, for example.

But manufacturers have been known to take advantage of the fact that all USB-C cables look alike. The cable that comes with something like an Amazon Kindle will feature the most basic of charging capabilities while connecting the USB 2.0 data pins for slow data transfer. Plug that cable into a monitor or a fast external SSD, and you're in for disappointment.

The problem is, with a drawer full of identical cables, you won't know that until you try it. Even then, it might not be immediately obvious that you're using a substandard cable for the job. And sometimes cables that you buy online aren't what they claim to be.

Unmasking false USB-C cable advertising

How cheap cables trick your devices

This is where using a simple cable checker can be so important. They aren't overly costly, and you can get one that checks both power and data capabilities for around $45. If you just want to see how fast a cable can charge, you can get one for considerably less. Either way, they can help you check whether the cheap cable you bought actually does what it says it will do.

A good cable tester will check whether your cable has an E-Marker (Electronically Marked Cable) inside. It's an integrated circuit inside the connector housing that can communicate with chargers and devices. An E-Marker holds the information needed for a good charger to know how much power the cable can handle.

Cables without an E-Marker are limited to a maximum of 3 amps (or 60 watts at 20 volts) for obvious safety reasons. Trying to charge a 16-inch MacBook Pro with 100 watts of power through a subpar cable could cause a fire.

I've found that testing cables doesn't always yield the results that you expect, and a surprising number don't live up to the hype. I generally don't keep low-quality USB-C cables around, so I can pick one up and be sure that it'll charge almost anything in our house. And yes, that includes our laptops. So with that in mind, I didn't foresee any surprises when I set about testing the handful of cables in my drawer.

But the thing about surprises is that they're unexpected. That's kind of the point, so it was definitely a surprise when one cable that claimed to support 100-watt charging simply had no E-Marker to speak of. Another cable claimed to offer high-speed data for an external SSD I use sparingly, but it couldn't beat the 480 Mbps of the USB 2.0 standard. Some of the cables I owned had E-Marker chips, but they reported data that didn't match what the box claimed. It was a mess, but now I know which cables to trust and which to trash.

No more cable surprises for me, thank you.

Take back control of your cable drawer

Time to audit your collection

You don't necessarily need a new cable tester to take control of your cable drawer, though it definitely helps. All you really need to do is use a trusted system that will help you identify a cable in the future.

Picking up a cable only to wonder what it can actually do is a problem many of us face all too often. But there's no better time than right now to audit your collection of cables, ready for the next time you need one. If you have a cable tester, use that. Otherwise, collect all known-good cables into a pile, and then it's time to get the label maker out. Print a label that details what the cable is rated for in terms of power and data delivery, and attach it. Keep going until you have no more mystery cables. Another option is to keep similar cables together, so they're easier to locate.

Now would also be a good time to purge those cables that either don't work or simply aren't up to the job anymore. Slow cables just don't cut it for modern devices. Jettison them now, before you accidentally use them in the future.

Moving forward, consider only buying cables from reputable manufacturers so you can trust that they can do what they say they will do.