You can find out Visa currency exchange rate here.
Important: Transactions foreign currencies are settled by Visa/Mastercard within 2-3 days. The transaction has two stages: funds are first held (pre-authorization) and then debited. In this case, the debit is made at the current exchange rate, not at the rate of the original payment day. If the exchange rate changes while the transaction is being processed, the debited amount will be different from the amount originally held.