The fee racket is a mess, they even charge you if someone sends you money unasked and then charges it back (can be up to a $20 fee)
On normal transactions, the fees can depend on the currency (if sending to someone in another currency), and then friends and family vs goods and services. I found this calculator online with all the different categories and their fees... painful...

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https://www.salecalc.com/paypal )