Check your frequent flier account online seven days after you've completed your journey. If you can't access your details, wait until you receive a statement. Make a note of the air miles you earned for one leg of the journey. If your account doesn't display this information, call the airline's customer service number to ask for it.
Visit Travelmath.com, select "Flight distance" from the "Get" drop down box and enter the code of the airport where you started your journey in the "From" box. Then put your destination airport code in the "To" box and press "Calculate." The distance of the journey in miles will be displayed.
Divide the number of air miles you were awarded by the actual miles traveled to calculate what you earned per airplane mile.
