The Best Time to Book Flights, According to the Data

There's a lot of folklore about when airfare is cheapest. After looking at millions of fares, the picture is simpler than the internet suggests.

Domestic flights

The sweet spot is roughly 21 to 60 days before departure. Inside three weeks, prices climb sharply.

International flights

Aim for 2 to 6 months out. Peak summer routes to Europe should be booked even earlier January and February are quietly the best months to lock in July travel.

What doesn't matter

• The day of the week you book.
• Clearing your cookies.
• Booking at midnight 'before fares refresh'.