Why does my card statement differ from the converter?

Your statement differs because your issuer applies its own rate when it processes the transaction, and that may be later than the purchase. The converter shows a reference rate for the latest working day, while the card network or issuer converts at the rate in force when the payment settles, and some issuers add a foreign transaction fee on top. Small differences are normal. To see how much conversion cost you, compare the dollars charged with the yen price converted at the reference rate for the transaction date.¹