Do the banks use Mastercard’s rate to do currency conversions? Or does it vary?

I need to find the exchange rate for a transaction on a given day in the recent past – so I don’t think I have it on the statements. Plus I cannot find them. Or my online banking details for that card… Mastercard has historical rates on their website so will that be the one the bank uses?

Isn’t the conversion rate printed along with the transaction on your statement?

(Apologies if by what you were saying, you can’t actually access the statement.)

Some statements are probably in this huge pile of mail.. but not the most recent ones.