When you're booking a flight, you don't want to buy too far in advance—and be the guy who lost out on a price drop; nor do you want to book too late—and pay hundreds more for the convenience. When's the best time to buy? CheapAir crunched the numbers from over four million tickets bought last year to offer some advice.


Those four million tickets add up to a database of 1.3 billion air fares. What they found, at least for domestic airfares, is there's a "prime booking window" of between 29 and 104 days in advance when the average fare is at its lowest (so, roughly a month to three months before the flight). Taken altogether, 54 days in advance is the best time to buy, based on this data.

As you can see from the chart above, the cost of waiting up to 13 days in advance is enormous.


These real-world findings back up one economist's calculation of the cheapest time to book a flight, eight weeks.

CheapAir notes, however, that the exact 54 days in advance number isn't very important. Prices for each trip will rise and fall volatilely depending on the market and when you're flying. As a rule of thumb, you should still keep checking fares frequently and grab a good deal when you see one.

When should you buy your airline ticket? Here's what our data has to say | CheapAir