Bitcoin ATMs can go two ways: one-way bitcoin ATMs or two-way ATMs. Only around 30% of the world’s bitcoin ATMs actually run in both directions. One-way means you can only either buy or sell bitcoins, while two-way allows for the transaction in both directions.
The ATM’s get their price from the internet and charge a fee ranging from 6.5% to as high as 25%. To repeat, some BTC ATMs charge as high as 25%!
On a two-way ATM, you can deposit cash into the machine and receive coins to the wallet address provided(usually by scanning your QR code). It can also works the other way by scanning the QR code and receiving the cash for your bitcoins. Currently most ATM’s actually only offer the ability to buy, though.