When should you buy your next plane ticket? According to a new fare study from Hopper, Thursday is the best day to book both domestic and international tickets.

Best day to depart: Wednesday, for both domestic and international trips.

Worst day to depart: Sunday, also for both types of trips.

Best day to return home: Tuesday (domestic) or Wednesday (international).

Worst day to return home: Friday (both).

The sad news; there's just a $10 difference between the best day to book and the worst day (Saturday) for domestic tickets.

Another study from earlier this month found that, on average, you'll get the cheapest fare if you book 54 days in advance of your flight.