If you’ve ever been alarmed to see prices for airline tickets spike within minutes of checking them, you’ve probably wondered if you’re missing out on a sweet spot for purchasing.
The answer is yes—and it’s on a Sunday. According to Conde Nast Traveler, a joint study by travel site Expedia and the Airlines Reporting Corporation used data [PDF] from billions of personal-travel bookings to decipher when travelers were getting the best airline deals. Passengers who booked flights on Sundays saved an average of 17 percent on domestic flights and 30 percent on European travel.
There is a caveat, though. In order to have a chance at the best pricing, Expedia found it’s best to book a minimum of 21 days in advance. (A ticket between Europe and the U.S., for example, was an average of $669 less expensive when booked more than three weeks before travel.) And you’ll want to avoid attempting any bookings on Friday, since you’ll be jockeying for seats with business travelers.
The companies found one other airline hack: Trips that include a Saturday night stay are generally cheaper (up to 19 percent for travel within the U.S.). Combine that with a 5 percent price drop for an average ticket in 2016 from the year before, and flying in 2017 could be easier on your bank account than ever before.
[h/t Conde Nast Traveler]