How AdSense determines the exchange rate for your earnings
We convert advertisers’ payments from their currencies to your payment currency using the prevailing market rate from the day before the ads were shown. We get our rates from major banks, and other industry-recognized rate sources.
For example, let's say you get paid in euros, and an advertiser purchases ads on your site using U.S. dollars on August 15. We'll then calculate your earnings using the dollar to euro exchange rate from the end of August 14.
The exchange rate for performance reports
We convert currencies in performance reports in the same way. This means that reports in your payment currency should reflect the amount you'll be paid. Reports in a different currency reflect the amount you would be paid if you were paid in that currency.