Gadget Review: Plugable USB-C Voltage & Amperage Meter (240W)

All USB-C cables are equal. But some, as the saying goes, are more equal than others.

This little gadget from Plugable is a fantastic bit of kit. Plug your USB-C power supply into one end of the gadget, plug the gadget in to your laptop, phone, or any other USB-C device. Watch the screen to see how much power is flowing.

Action Shot


  • A black and white screen!
  • A button to flip the display over!
  • That's it!

There's no Bluetooth or WiFi to get the results out. There's no flash storage to record anything. There's no graphs. It shows you volts, amps, watts, and direction of power. That's all I need it for, and that's all it does.

As you can see, the screen reacts quickly. So you can get a good idea of what power load your various apps have.


This is great. My work Windows laptop was complaining that it wasn't receiving enough power from my USB-C docking station and, with this, I was able to see that it was getting about 40W.

I was able to test some USB-C cables to see how much power they could support.

Even better, this doesn't interfere with normal USB-C functions. It happily passed through video, audio, peripherals, etc.


It's about £20 - £35 online depending on whether The Algorithm favours you or not. You can find cheaper ones - but they tend not to go up to 240W.

This is an indispensable gadget - especially if you have dozens of cables of uncertain provenance. It'll tell you just how much they're capable of delivering.

Now I just need to find a USB-C plug which can actually deliver 240W via PD!


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6 thoughts on “Gadget Review: Plugable USB-C Voltage & Amperage Meter (240W)”

  1. Passive USB-C cables support up to 60W, anything higher needs more expensive cables with e-Marker chips on both ends, which are actually ARM32 MCUs that will tell both sides their capabilities and negotiate power. So the power source, sink and cable are all involved in a 3-way dance.

    If you want to learn more, I'd suggest following Benson Leung, a member of the Google Chromebook team who started a one-man charge against shoddy USB-C cables and chargers after a defective one burnt his laptop.

    You could also splurge on a USB-C tester like those made by ChargerLab.

  2. Gui says:

    Cool little gadget! I wonder if there’s a similar one for HDMI cables.

    1. @edent says:

      I had a Denon amp which had an HDMI diagnostic function. You plugged the cable into the input and output, then ran tests to see what speed it was rated at and what features it supported. Very useful.

  3. says:

    @Edent Kinda-related: Used a gizmo like this recently to work out why crappy $oldjob Dell complained about many of my USB-C chargers.

    Realised Apple seems to ask for power-level it wants based on battery level etc but Dell tried to demand 96W (more than most of my travel chargers offer) briefly when connected even if it fell back to requesting much less. That spike generated the complaint.

  4. says:

    By pure happenstance I was watching a data transfer to an nVME SSD running super slow one day and realized that the USBC cable I was using for it only supported USB2. Because it was a "high power charging cable" and only provided a data connection by coincidence.

    Is there something equivalent for winnowing out terrible, horrible, very bad, no good cables like that?


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