How to measure USB cable data transfer speed, charging speed

You can check the Apple System Profiler "Power" section and "USB" sections respectively. And to test the speed, you can use an app such as BlackMagic Disk Speed Test, but make sure to configure it to select the external drive since it defaults to the internal boot drive. Of course your external SSD must be capable of actually reaching speeds of 10Gb/s.....you must ignore the advertising hype of the USB-C or USB3 references since they will always mention 10Gb/s even when the drive is physically unable to reach those speeds since the vendors are just advertising the wonderful max speeds of the USB3 protocol.

You should be using name brand high quality cables, otherwise you will end up with who knows what....sometimes you may get lucky & get a good quality cable, but usually you will get junk. Most quality cables for a particular specification will cost about the same from all manufacturers & vendors.....whenever you see an incredible bargain (barring a sale), you are most likely being cheated or scammed.

macOS does not include a UI for the cable detected past the Apple > About this Mac > System Report > Hardware > USB mentioned above. Linux does have some (arcane) canlevreporting ability here, though.

10 Gbps is relatively slow. That’s USB 3.2 gen 2x1, or USB 3.2 gen 1x2.

Here’s an overview of the USB-C cabling which might help understand the mess:

https://people.kernel.org/bleung/now-how-many-usb-c-to-usb-c-cables-are-there-usb4-update-september-12

Thunderbolt cables do both Thunderbolt and USB.

There are USB testers available, but various of the inexpensive USB cable testers check pins and continuity and don’t include PD. (Plugable has an inexpensive USB-C meter rated for 240W EPR, but that’s a meter and not a means to directly check the wattage permitted by the cable itself.)

PS: A correction to a reply above…

Here are the current USB-C cable logos (these differ from the USB 3.x labeling):

https://www.usb.org/sites/default/files/usb-if_usb_type-c_cable_logo_usage_guidelines_final_20230818.pdf

a genuine USB 3.1 cable is rated as SuperSpeed Plus, up to 10 G Bits/sec.

it has this USB logo on it:

to attain 20 G bits/sec, the port MAY be able to momentarily 'turn around' the Inbound data pathways into Outbound data pathways.

If no such logo, stamped on the cable or on a certification tag, you are trusting that there maker told you the truth.

Brand-X cables have no maker (with a reputation to defend) standing behind them.

<<. You can't trust logos either mate - easy enough to stick a fake one on. >>

Brands that have reputation to defend chase down the fakes and get (some of them at least) off the market.

But you don't buy stuff from guy standing on a street corner expecting it to be genuine.

And I repeat: Purchasing from trusted reputable vendors is also required.

And in case that is not enough......purchase only directly from the manufacturer themselves such as from a physical Apple Store location, or directly from www.apple.com. But earlier you deemed this off topic for some reason. I'm beginning to suspect you are trolling, or you have some extreme phobias that need to be addressed with professional help, or you are looking for super cheap bargains & hoping to get quality products (rarely happens....cheap products are usually cheap in both price & quality).

I'm bowing out of this thread since you seem to be looking for a unicorn......it doesn't exist. You've already been offered multiple replies by very knowledgeable & tech savvy contributors. Both @Grant and @MrHoffmann are both very knowledgeable & respected contributors.....I've learned so much from both of them.

since you posted your query in the MacBook Pro section of the Apple support forums, I already figured out roughly what was on the computer end.

I specifically asked about the OTHER end. What devices?

Because in some cases, that cable, even if true to its description, is inadequate.

newzild wrote:

I’d be grateful if comments could address the question in the original post, please.

Run the performance tests mentioned, connect to Linux or with one of the testers mentioned and check the pinouts, and compare the performance with a known-good cable. There isn’t a “check for a junk cable” option.

newzild wrote:

Not trolling.

The reason this is off-topic is that I already own the cable and have discarded all packaging, logos, etc.

My requests to stay on-topic nevertheless fall on deaf ears!

Ever heard of the sunk-cost fallacy? This cable has already wasted more of everybody’s time than it’s worth, and further performance testing and continuity testing adds to that time and effort cost. Replace it. Preferably with a cable appropriately specified from a reputable vendor, and—though not a panacea—with a certified logo.

Purchasing from trusted reputable vendors is also required.