On travel tickets

Every year at CheapAir we go through a little exercise.

We take a list of the top 15, 000 markets where our customers live and like to fly to, and we watch fares between those cities over the course of an entire year.

It’s actually more than a “little” exercise. In 2014, it amassed to 1.5 billion airfares as we watched 4, 986, 522 trips, recording the lowest fare for each trip every day from 320 days in advance up until one day before flight time. It’s a treasure trove of cool info if you’re an airfare geek; or, a curious use of terabytes, if you’re anybody else.

Since the majority of questions we get asked every year start with “When is the best time to book my flight to…”, the first thing we always do with this data is determine, on average, how far in advance should you book your flight to get the lowest fare.

This year, for domestic flights, the answer is 47 days.

Now, if our database could talk, it might protest having to give just one number for when to buy. As we have found in years past, the average is just that: The Average. There was, and always will be, quite a variance across the five million trips we reviewed.

Here’s an example: If you happened to fly from Boston to Detroit for a seven day trip starting on February 13, there were actually some fantastic (and rare) last minute sales. In that case, booking the day before the flight was the best day to book. This is extremely rare, and waiting until the day before travel is something we never advise. At the other extreme, there were trips like Austin to Orlando, leaving on July 11 where your best bet would have been to buy 320 days in advance.

The point is, for individual trips, the best time to buy varies substantially depending on the destination, time of year, and travel days. So think of 47 days as a guide, not an exact day you should book. And on average, booking later than 47 days will always carry more risk than booking early.

Here are 5 additional pieces of advice that we are able to glean from this massive study. Keep in mind that our focus here is on domestic flights – those within the U.S. Click here for our discoveries about the best time to buy international flights.