With Square, the transaction fee is simple: you pay 2.6% + 10¢ for every card accepted through the card reader. There’s only an additional 1% charge if Instant Transfers are activated; an optional setting that transfers payments to your bank account immediately rather than the day after (the latter is free).
There are no additional Square fees for international or premium cards, or currency conversion.
Stripe Terminal’s base transaction fee is 2.7% + 5¢ for all cards, but international cards cost 1% extra, with currency conversion incurring an additional 1%. Bank account payouts are free, but like Square, Stripe offers optional instant payouts for an additional 1% fee.
Now, if you choose Stripe Terminal’s mobile card reader and use one of the ready-made payments apps, you also have to add an extra transaction fee for your chosen app: 1% to the Payment app, or 1.3% to the Collect for Stripe app.
That means you pay a minimum of 3.7% + 5¢ with Payment, and 4% + 5¢ with Collect. If you accept an international card, it’s 4.7%-5% + 5¢, or 5.7%-6% + 5¢ with currency conversion too.
Integrating a Stripe reader with your own app shouldn’t incur app-based transaction fees, but there may be costs for other compatible payment apps not mentioned here. Square has no such app fees – it is completely free to use Square Point of Sale with Square Reader, and the same goes for Square Terminal’s software.