The Best Time to Book a Domestic U.S. Flight is 54 Days Out

Finding the cheapest flights isn’t as easy as it used to be. With high fuel costs, always-full flights, and razor-thin profit margins, the days of ubiquitous, sub-$100, cross-country flights are over. But, if you time your air travel booking just right, it’s still possible to save a bundle. A massive study conducted by CheapAir.com calculated the best formula for finding the cheapest possible airfares.

Every year, CheapAir.com pores over data for more than 900 million airfares. They found that, for any given trip, fares can change more than 75 times and more than $30 each time! So, if it often feels maddening to know when to book your trip, you’re not alone. The bottom line is that it (literally) pays to know the best time to book. For the second year in a row, that magic number for domestic, U.S.-based flights is 54 days ahead of your trip.

The study outlines several distinct windows for booking your airfare, each with their own pros and cons:

Booking more than six months out typically results in the highest fares, but the most flexibility since almost every flight option is available to you. Expect to pay about a $50 USD premium.
Securing your flights 3.5-6 months in advance comes with a slightly lower premium (around $30 USD), but still plenty of flight options.
CheapAir.com calls three weeks to 3.5 months in advance the “prime booking window.” This is a large window, but it’s when airlines develop a clearer idea of their availability and how to price their tickets according to demand. Fares are typically within 5% of their rock bottom price.
In the 2-3 week window ahead of your trip, you’re essentially gambling. This is already passed the prime booking window, so flights are filling up or full and fares are likely to be higher. But, it’s possible to find a rare deal.
At the absolute last minute — less than two weeks before your trip — you’re at the mercy of the airlines. Most routes fly full or close to full these days, so you’ll be paying a hefty premium. Whatever you do, don’t book the day before your trip or you can expect to pay almost $250 more on average.

It’s worth noting that the 54-day rule is more of a guideline and applies only to domestic flights within the United States. Canada air travel is similar. However, other destinations — including Europe, Hawaii, and the Caribbean — can vary even more widely.

Once you get your flight settled and you finally board the plane, treat yourself to this travel playlist: