According to a recent study by Expedia, the cheapest day to book flights is Sunday. When comparing Sunday flight prices to Friday, Expedia found that travelers save 5% on domestic flights and 15% on international flights. For the past four years, Sunday has been the best day of the week to book flights.

According to the 2026 Expedia Air Hacks Report, the best day of the week to book a flight is now Friday. Historically, Tuesday was cited as the "deal day," but recent data shows that booking on a Friday can save travelers roughly 3% on domestic flights and up to 10% on international routes compared to Sunday, which is consistently the most expensive day to book. However, the day you fly often matters more than the day you book; Tuesday and Wednesday remain the cheapest days to actually depart, offering savings of up to 14% compared to weekend travel. For the best value in 2026, travel experts suggest setting price alerts and booking domestic trips 28 to 35 days in advance, while international economy fares are best secured roughly 3 to 4 months before departure.