Info info - Want to buy a charger for your device that comes with no charger?


Sep 18, 2019
If you want to buy a charger for your smart watch, bluetooth earbuds/headphones, etc because they only came with a USB cable and it's not convenient to have them charging in your computer, etc., here's what you need to know to buy a charger:
They are measured in Volts and Amps.
USB ports 1.x, 2.0 - black plastic have a standard power output of 5V 500mA (or 5V 0.5A).
USB ports 3.0 - Blue plastic have an output of 5V 1A.
Fast charging ports vary, they can be 5V/9V/12V and have 3A/5A/9A. The lowest for fast charging is 5V 3A.

If your USB cable has a Black plastic, you need to match the charger to USB port 1.x/2.0; if it has a blue plastic, match it to USB 3.0 (charger will also have a blue plastic).
For Fast charging cables (any other color generally green or purple), unless the manual or the box says how many volts and Amps the device needs, buy a 5V 3A charger. You can always go down on V/A, you can even use a 5V 1A charger (equivalent to USB 2.0) on a fast charging device, but you can't go up. if your device uses 5V 3A, trying to charge it with 12V 9A might damage your device.
The way you know if the charger has the correct output is by looking in the box or the charger itself: on the small letters of a charger, it says the output, among other information.


Mar 25, 2010
USB 3 ports are mostly blue but that is on a computer not on a charger, the chargers do not rate the ports as USB 2 or 3 since that is as much for the speed of data transfer as the power output the port can do. The chargers are rated for the power output not USB type, although there may be some that list "USB 3" port where it's really not and they are just using it because someone may have heard something about USB 3 being good so they want that term in the search.

You can't just go by color of the cables as to what they support, need to read the product specifications.
A few things here:
  • The USB specification has a lot of different standards for power delivery, and they don't necessarily apply to just one type of port or the other. I've seen USB 2.0 ports on computers happily supply more than 500mA. USB chargers with Type-A ports use USB 2.0 ports for economy reasons (because they don't care about data), but they'll also happily provide more than 500mA.
    • As mentioned, the color of the USB port isn't indicative of its power delivery capabilities. For example, Anker's PowerCore 10000 Slim uses light blue colored USB ports, but the actual port is a Type-A 2.0 port, and it also supplies 12W (2400 mA at 5V)
  • A USB port must gaurantee 5V is available. If a device or charger/port/whatever can supply a higher voltage, the device must communicate that first before the port bumps up the voltage. For example, a USB-PD charger that can supply 12V will not feed a USB device 12V unless the USB device says it can support this. Otherwise the charger will only supply 5V.