People who travel often, whether for business or pleasure, belong to frequent flyer programs associated with their preferred airlines. Building up air miles within a frequent flyer program awards you with special offers such as a free class upgrade, discounted hotel rooms, and even a free ticket. Air miles, however, use a different system than other forms of transportation, such as cars or trains.
To easily calculate air miles between two airports, use a website such as Webflyer and enter your three letter departure and arrival airport location abbreviations. Some websites will allow you to enter the city name and generate the three letter abbreviation for you, so it's okay if you don't know it. Don’t forget to include any connecting destinations on your travel itinerary, as well. Different connections can have different air miles results, even if traveling to the same destination.
Next, if you're using Webflyer, click on the “How Far” button to see your results. This will tell you the air miles for both a one-way and round trip ticket, including any bonuses you may have entered. Using this tool will ensure that you will always maximize the amount of air miles you receive for each trip.