Accruing airline miles is a game to most people but trying to figure out what the miles are worth practically requires a PhD in economics. To help you decide if you should pay with miles or cash, check out this “Mile Value Calculator.” The blog that it’s located on isn’t the most eye-pleasing but it’s an interesting concept. Just input the Ticket Value ($), Taxes and Fees ($), Miles Used and Miles Foregone (the amount of miles you would earn if paying cash). You can figure out that amount by using the Great Circle Mapper. Once you hit calculate, the number will show up at the bottom of the screen and you can then decide if it’s worth it or not. I usually like to get at least 2 cents per mile spent.