Find Out How Much Power USB Devices Need

Martin Brinkmann
Jan 8, 2011
Updated • Jan 28, 2015

Each USB port can provide power to connected devices. This is not always necessary, especially if the connected devices have their own external power supply.

But some devices need the power provided by the USB port to function or reload batteries. A problem with this is that USB ports can only supply a maximum of 500 mA (that's milliampere) which is usually not a problem if one device is connected to the port.

It could become a problem if a USB hub is connected to the port that is powering multiple devices as it could mean that the required power exceeds the maximum power that can be supplied by the port. which in turn can result in connection problems and even data loss.

A good start is to find out how much power USB devices need before connecting them together to an USB hub.

The free portable software USBDeview by Nirsoft can do that. Just download the software, unpack it and start it on the target computer system.

Power is one of the information provided by the application. You need to scroll a bit until you find the column as it is located near the end.

You need to click on the Power column title to sort the devices. Not every device requires power and this brings those that do to the top of the list. It is not always that easy to identify devices.

The description and drive letter usually help out here. You can also try and disconnect devices and refresh the listing to identify it by looking at which device is missing from the listing after the disconnection.

If many devices are connected to your PC that require power, you may want to consider connecting them to different USB ports to make sure that the power they receive from it is sufficient for their operation.

Did you ever run into troubles running multiple USB devices on one USB port?


Previous Post: «
Next Post: «


  1. fivish said on September 14, 2015 at 12:28 am

    I have a usb flash drive that works just fine but when I plug it in USBDeview crashes. All my other flash drives appear on usbdeview as expected. Why this drive crashes usbdeview?

  2. alan said on June 14, 2011 at 2:19 pm

    An odd title for your page. mA are units of current, not power. how much power (Watts) can a USB provide?

  3. Randal said on January 10, 2011 at 1:05 pm

    How come my portable hard drive its only 2 mA? No external power needed…

  4. Martin Watson said on January 10, 2011 at 10:39 am

    My USB microscope specifically requires a direct (not via a hub) connection. I’ve never understood this. It won’t work via a hub.

  5. iphone repair orlando said on January 9, 2011 at 5:01 pm

    I agree to you Roman. There are some devices that needed to be recharge with USB.

  6. CypherHackz said on January 9, 2011 at 1:19 pm

    Wow! It is very cool software. This is the first time I saw a software can check how many power a USB device need when connected to the computer. Thanks for sharing boss… :)

  7. Jonathan said on January 9, 2011 at 6:04 am

    FYI: These number can be obtained with no software at all.
    Goto the “Device Manager”
    Under “Universal Serial Bus controllers
    Look at all the USB Root Hub entries
    Right Click on each on and hen Click on the “Power” tab

  8. rickxs said on January 9, 2011 at 12:08 am

    Barney ,go to view – choose colums then use ‘ move up ‘ for power to show easier in the listing

    Great post Martin –just what I been wanting!! , I have a usb camera that wont charge to full in my pc ,yet in my sons it does with no problems – now I can see what’s happening


  9. barney said on January 8, 2011 at 9:57 pm

    I’ve used USBdeview for a while, through several iterations. I’ve yet to see any indicator for power consumption. Just how did you acquire the power consumption listing?

    1. Martin said on January 8, 2011 at 11:59 pm

      The feature was added in a recent version, maybe yours is not up to date?

  10. Roman ShaRP said on January 8, 2011 at 9:47 pm

    Not a trouble, but an issue: my e-book reader can be recharged with USB. and it can be recharged well connected to a USB port, but once I connected it to a hub – and it couldn’t be recharged for all the night :)

Leave a Reply

Check the box to consent to your data being stored in line with the guidelines set out in our privacy policy

We love comments and welcome thoughtful and civilized discussion. Rudeness and personal attacks will not be tolerated. Please stay on-topic.
Please note that your comment may not appear immediately after you post it.