Determine the itinerary. A trip from Austin to Los Angeles may be routed through a second city, like Dallas or Detroit. This route for instance, would have two legs, Austin - Dallas and Dallas - Los Angeles. If both legs of the flight have the same flight number, the flight is considered direct and not non-stop. When a flight is direct, miles will only be given for the distance between the origin and destination. In that case, the route for calculation would be Austin - Los Angeles.
Calculate the distance between airports for each leg of the trip. There are websites that will calculate the approximate distance of each leg for you. Working with our previous example, Austin to Dallas is approximately 190 miles and Dallas to Los Angeles is approximately 1235 miles.
Read the airline's Frequent Flyer program rules to determine if the airline has a restriction on the minimum miles per leg traveled. Many airlines award a minimum of 500 miles for each leg. If the airline has a minimum awarded distance use that number, even if the actual distance is lower. For example, 500 is greater than 190, so you would use 500.
Add the mileage from each leg of travel together to calculate the Frequent Flyer miles that should be awarded. So our sample journey would constitute 1735 miles. 500 from one leg plus 1235 equals 1735. Any bonuses offered by the airline would be in addition to the 1735 miles.
