But what is the actual exchange rate used (compared with, say, citi debit visa)?
Is any arbitrage built in?
I did some comparisons a few weeks ago before a trip to Indonesia, as I was curious which of my credit cards would give me the best rate for purchases.
The exchange rate at xe.com was IDR
9940 for AUD$1 on the day I made the comparisons
I got the bank's exchange rates via their websites and/or talking to them.
To make for easier comparisons, I worked out how much 1 million Rupiah would have cost in AUD if I had made the purchase that day.
CommBank Diamond: exchange rate $1 = IDR9009 plus 3% fee
-> 1 million Rupiah = $114.33
Bankwest Platinum: exchange rate $1 = IDR9190 no fee
-> 1 million Rupiah = $108.81
Westpac KF Platinum: exchange rate $1 = IDR9054 plus 3% fee
-> 1 million Rupiah = $113.76
Citibank Prestige: exchange rate $1 = IDR9803 plus 3.3% fee
-> 1 million rupiah = $105.37
So the Bankwest "no fee" deal is pretty good, but the Citi Prestige is better even including the fee.
I haven't gone back and done the comparisons on a different day, nor have I checked any other currencies - so I don't know if this was a fluke or if the Prestige will always serve me best - but with 5 points per $1 (=3.33KF miles per $1) on international spend it would have most likely been my weapon of choice even if it wasn't the best exchange rate.
Indonesia isn't on Citi Australia's online list of exchange rates but their call centre advised me to use the exchange rate calculator at usa.visa.com - I would link to it directly but haven't made enough posts on this forum to do so.
I compared the usa.visa.com exchange rates with purchases made overseas and it is spot on.