Stripe transaction fees vary by payment type, but the standard online rate is 2.9% + 30¢ per transaction. Other fees can apply for international cards, currency conversion, and alternative payment methods like ACH direct debit. (read more about it here).
To protect your margins, you can opt-out of Stripe Fees by passing them along to your patients. This only will show as a small "2.5% Service Fee" when your patients go to pay on your app's checkout.
To pass along Stripe fees to your patients, go inside "App Builder" > "Settings" and scroll down to the bottom until you see "Transaction fees". Simply toggle it on.
This means that if a patient has a total cart value of £200, and decide to checkout, they will pay a Service Fee of £5 (2.5% of £200). This number will appear under the summary total.
This will mean your business will only pay 0.8 + 30¢ (2.5% - 2.9% + 30¢ = 0.4%+ 30¢), which is a smaller number compared to what you would normally pay: £6.1!