I've never used Raspberry Pi before. I've got myself Model B but it didn't come with its power supply. On their official website I've got this info: You need a good-quality power supply that can supply at least 2A at 5V for the Model 3B. But, since it says al least, it makes me wonder, how enough is that? Asking because I have a 5V 2A power supply at home and I'm afraid that it can fry it if I use it. I plan on using Pi at the moment for symbolic circuit solving so I don't think that would require any more than 2A.

  • "At least X" means "X or more is OK". So X is OK. Commented Dec 19, 2019 at 17:21

3 Answers 3


Every process increases the current consumption of raspberry pi. If you are using Graphical interface, your consumption will be higher instead of command line interface. I've powered up the raspberry pi with USB 2.0 which provides just 500mA. But problem arises when used with heavy applications.

So you can use your source without any worries. Raspberry Pi will draw only the required amount of current out of 2A.


I'd recommend to buy the official Raspberry Pi power supply and NOT use old phone chargers.

The reason is simple:

  • Phone chargers are intended to deliver a constant current for charging the battery. Hence the name. They are not suited for variable load like a Raspberry Pi that draws different amount of current depending on what it is doing right now.
  • The official Raspberry Pi power supply was designed to accomodate this particular usecase and therefore can deal with variable load much better.

I do not say that other USB chargers might not work. But it is my experience that those may or may not cause issues that are hard to track down. Like short undervoltage when starting a heavy task or instant reboot when connecting a USB device to the Raspberry Pi or general system instability.


That should be fine. Try it and see. It will not harm the Pi.

I invariably use my Pi's headless (no screen or keyboard) and quite often use wall warts rated at less than 2 amps without a problem.

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