According to a 2011 study conducted by FareCompare, the cheapest day of the week in which to fly within the United States was on Wednesdays, with Tuesdays and Saturdays as close runners-up. These are the days with the fewest filled seats of the week, so airlines discount these days to try to fill empty seats. The rule is not a hard and fast one, however, as discount airlines such as Southwest and Spirit are likely to have their own patterns for fare sales or discount days, or perhaps none at all. This also doesn't apply to international fares.
FareCompare's study also found the cheapest day on which to purchase your ticket (as opposed to the day you are flying) is Tuesdays at 3 p.m. This is because airlines launch their weekly sales on Monday nights, when tickets can be discounted 10 to 15 percent. Competitors then must match these sales, which typically expire by the end of the week. Again, discount airlines whose prices are more fixed and don't fluctuate according to competitor sales aren't as likely to follow this rule.
The best times of the year to fly are during holiday and vacation lulls. This typically is the first two weeks of December, when in the U.S., travelers usually stay home between Thanksgiving and Christmas, and after New Year's continuing into March. International and domestic flights can be heavily discounted for these times, as many travelers avoid vacationing in the winter and are saving money after the post-holidays season. There also is a drop in ticket prices just after the summer season, when vacation travel sharply drops.
According to a 2011 study by the Airlines Reporting Corporation, passengers who booked 42 days before their flights saved the most money. This is an average, but the trend held for the four-year period analyzed by the agency. This goes against the old adage that the farther out you book your travel, the better. If you are flexible and willing to take the risk, however, some airlines may have last-minute flight deals.
