How profitable are international wire transfers for banks?

Hardly any on the wire transfer fees, as that barely covers the cost of the network they use to send the wire across. Maybe 10% to 25% of the fees at best.

On the wire amount itself, banks can make a lot of money via two ways:

• Float on Currency (release the money 1, 2 or even 3-4 days later). That money is used to lend overnight and earn interest on it.
• Exchange Rate Conversion (Parity) where applicable (i.e. converting from original remitted currency to the default currency of the host country where the money was sent), banks can make anywhere from 0.25% to 5% on the amount received. It all depends on how they are structured and how much flexibility they have (via regulators) and market acceptance (as in is everyone doing it? is there competition that prevents them from making so much money on exchange rate conversion).