Originally Posted by
percysmith
So I think the acquirer determines what Visa rate we get, by controlling the time of posting.
And you won't get exact rate either because even if you are in the same timezone as the Visa website, the Thai/Chilean/Australian acquirer isn't.
I think you might be onto something here. I had two transactions both on June 7th according to Chase that posted on June 10th. The earlier one from the afternoon had an exchange rate of AUD:USD of 0.936740262. The later one from dinner had a rate of 0.936742934. The Visa rate for June 10th was 0.936706. In neither case do I get a different result by using the Visa exchange rate, so I think at least for Chase cards it's easy to tell exactly how much the transaction would have been had you used the Visa exchange rate if you get hit with DCC.