Originally Posted by
Syzygies
I keep a screen grab of the "Mileage Estimator" with details expanded, for every purchase. One can see this before completing the purchase, so if one forgets or buys over the phone, one can duplicate the information. The word "Estimator" is troubling, but so far these grabs have never been wrong for me. (I too track everything in a spreadsheet. I once made United 1K by $38. That's my idea of cutting it close.)
The disclaim any errors in the estimator and there was a case a few years ago where it was giving wildly inaccurate results for Canadian origin tickets. Your email ticket receipts have the details needed to calculate MQD's in the Fare Details section which lists base fare and fare components (including airline surcharges).