What You Need To Know About Booking Your Flight

03/09/2015 01:45 pm ET | Updated May 09, 2015

(Photo: Ticking Clock/Shutterstock)

For at least two decades, industry experts have been speculating about basic timing factors in finding the lowest airfares. The big question: When is the best time to buy plane tickets? So far, nobody has been able to come up with definitive answers that stand the test of time for very long. But that doesn't stop them from trying. There are numbers-based guidelines touted by travel experts. And there are tools and data that can help you ascertain the right time to buy. Here's the latest information on mastering the art of airfare booking.

How Far In Advance Should I Book My Flight?

Several sources publish data on the correlation between advance purchase period and airfares. The ideal time to buy a domestic ticket is 54 days in advance, says CheapAir, or seven weeks ahead, says Expedia, which are essentially the same findings. For international trips, the ideal period is 171 days ahead of departure, according to the same Expedia report. CheapAir refines the estimates: 96 days before trips to Europe and 96 days prior to Latin America trips. Both sources indicate that you can come close to the absolute lowest price over a wide range of dates: CheapAir's "window" for good deals on domestic tickets is 27-114 days in advance; Expedia's window is 50-100 days.

Avoid booking too early and too late. Too late is especially bad; you pay a huge premium for buying within a week or two of departure--even on airlines that nominally assess no advance-purchase limit.

What Time of Day Should I Book My Flight?

According to urban legend, you should buy on Tuesday mornings because airlines dump new fares and seat allocations on Monday nights. It's also rumored that travelers shouldn't buy on weekends, as consumers lap up the seats allocated to the lowest fare buckets on Saturdays and Sundays, leaving less low-priced inventory.

Here's what George Hobica, founder of our sister site Airfarewatchdog, says: "No one can accurately predict where airfares are heading any more than we can predict the stock market."

Hobica's blog points to a quote from an airline revenue manager on the subject: "To say that there is one time of the day or one day of the week that is better than another is false. Plus, fares are so dynamic, since they are based on market conditions and the actual number of passengers who are currently booked on a specific flight, that they can change rapidly at any time."

But the manager goes on to contradict himself a little bit: "Many airlines tend to announce sales on a Monday, leading other airlines to match certain fares the following day, but this is not a hard and fast rule."

When Do Plane Tickets Go on Sale?

The best time to buy an airline ticket is when it's on sale; that means you have to stay on top of the airline marketplace. Airfare sales crop up at random times. Typically, the purchase window is short--sometimes just one day, often a few days to a week--but the sale fares are usually good for a month or more.

As Hobica puts it, "Pounce when there's a deal." And remember: With almost all U.S. airlines, you can cancel your ticket within 24 hours of booking at no charge. Even if you've already bought your fare, you can keep looking for a better offer within that 24-hour window.

How Do I Stay on Top of Fare Sales?

Unless you enjoy the prospect of spending much of every day searching airline and OTA websites, the best way to keep on top of airfare sales is to subscribe to one or more airfare alerts. You have a range of choices. And we can help. Start with our own free fare alerts, our sister site BookingBuddy, and Airfarewatchdog's famous fare alerts. In addition, many individual airlines, big OTAs, and metasearch systems offer airfare alerts or promotional bulletins.

Keep two important factors in mind when you search: First, Southwest fares are not available from any OTA or metasearch system; you can get these alerts from the SmarterTravel, BookingBuddy, and Airfarewatchdog links above or from Southwest directly. Second, any time a big airline announces a sale, competitors usually match it, at least where they compete directly, within 24 hours. So always take some time to shop around before you book.

What Are Some Other Ways to Get Fare Alerts?

You can get fare alerts directly from your favorite carrier. Many airlines offer weekly or periodic email notifications of special sales and other useful information. It's a good idea to set up alerts from an airline with which you frequently fly, especially if you collect miles.

Many OTAs and metasearch systems also offer regular airfare-deal bulletins, including the two giants, Expedia and Priceline.

Or download an app. Airfarewatchdog and Skyscanner are two apps that tell you when to buy.

--By Ed Perkins

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Read the original story: When Should I Buy My Flight? by Ed Perkins, who is a regular contributor to SmarterTravel.