It's common knowledge that flight ticket prices tend to fluctuate wildly, and really, for us normal folks, it's almost impossible to keep up with all the constantly changing prices. Worry not, however, as there are studies, such as cheapair.com dedicated to studying flights and their prices, giving us the information we need to make the best consumers' decisions.

Credit: Cheapair.com

The most asked question we get here at CheapAir.com is “When is the best time to buy my airline ticket?” With frequent fluctuations in airfare prices, it’s no wonder that buying a reasonably priced ticket can often feel like trying to hit a moving target.

With the CheapAir.com 2018 Annual Airfare Study, we aim to provide consumers with current, straightforward information and insights so shopping for flights can be as transparent, inexpensive and painless as possible.

It all starts with analyzing airfares – this study looks at 917,000,000 of them in more than 8,000 markets. We take these airfares and break down the important data points, including:

– The “prime booking window” when flights are cheapest

– How airfares trend from the day they go on sale until the plane departs

– Worst and best days of week to fly to save money on airfare

– Seasonal airfare trends, including insights on the summer travel season

One interesting finding is that the lowest fare for any one trip changed an average of 62 times during the period that that trip was offered for sale. That’s roughly once every 5-6 days. Furthermore, each change represented an increase or drop of $36, on average.

So now you might be saying to yourself—great. How can I stay on top of all of these changes in order to get one of the lowest fares? Don’t worry! The goal of our study was to make it so that you don’t have to. We crunched a lot of numbers to reveal important insights that can save you time, spare you some work, and ultimately help you get a great deal on your next flight.

In 2017, for flights within the continental U.S., 70 days in advance was the best time to buy your airline ticket on average. This is a bit higher than last year, when the magic number was 54 days in advance.

Now before you go setting calendar alerts to remind yourself to buy all upcoming flights precisely 70 days out from your ideal travel date, keep in mind these are average numbers. And while averages can be a great guide, they should not be thought of as hard and fast rules. When you drill down into the individual trips, the best time to book varied based on markets, travel dates and the individual traveler preferences. This variation is captured by what we call the “prime booking window.”

The 6 Booking Zones – Including the Prime Booking Window

If you can imagine that there’s an optimal window for getting the lowest price, then it only stands to reason that booking at other times offers certain benefits and risks. Last year we broke the entire window of time when a flight can be booked into 5 specific booking zones. This year— we added another. Here are the booking zones:

First Dibs

169-319 Days in Advance

(approximately 6 – 11 months)

If being the early bird is your style, then you’re in the “First Dibs” (169-319 days before travel) zone. When you book this early you’re almost certainly going to pay a premium for airfare (about $50 more on average), and you’re going to watch people on your flight get better “deals” in the future when fare sales start to kick in. The airlines like to allow themselves the wiggle room to adjust flight price when the demand (or lack thereof) becomes apparent. But there is still a good argument for buying early. When you buy early you have a bevy of flight options that can shrink as the flight dates get closer. When you’re at the head of the line you can choose your seat (and make sure your group sits together), and fly at the time you prefer, getting the pick of the best itineraries for any given pair of cities. So you might find it worth the extra cash.

Peace of Mind

122-168 Days in Advance

(approximately 4 – 6 months)

We call this zone “Peace of Mind” (122-168 days before travel) because it alleviates travel anxiety and will cost you a bit less than “First Dibs.” If paying around $20 more for better flight options doesn’t spook you and you’re not much of a gambler, “Peace of Mind” might be just the ticket. You’ll lock in flight dates and still have a decent number of flight and seat options from which to choose.

Prime Booking Window

21-121 Days in Advance

(approximately 3 weeks – 4 months)

We now come to the “Prime Booking Window”, occurring 3 weeks to 4 months in advance, and otherwise known as the best zone to nab a bargain. Hunting for cheap airfare? Focus your efforts here. Its not as though you won’t see fares change in this zone but fares average within 5% of their lowest here, and you’re most likely to see a cheap fare pop up.

Push Your Luck

14-20 Days in Advance

(2 – 3 weeks)

Like to gamble? Miss your chance for the “Prime Booking Window?” If this is your scenario, the next option is the “Push Your Luck” zone (2 to 3 weeks before travel). This close to your travel dates, the fares usually climb and a lot of the aforementioned options are selling out. However, there are pockets of luck in this zone. We can’t make you any promises but some of those lower fares may still be available. Go into this zone with eyes open – Christmas week and popular high season destinations do not have the best odds. Less popular destinations or shoulder/low season travel might be a better risk. But be warned: even though sometimes the fare might not be that much more than if you had booked earlier, the same might not be true for seat options. Most airlines only offer a limited number of seat assignments for free; the rest of the travelers have to pay more to guarantee an aisle or window. The later you book, the less likely those free seat assignments will be available. Of course, you can always let the airline pick a seat for you for no charge, but if you care where you sit, this is something to consider.

Playing with Fire

7-13 Days in Advance

(1 to just under 2 weeks)

Some people just can’t help themselves – and like to fly a bit too close to the sun. Does this sound like you? If you’ve waited to buy your tickets so late that you’re “Playing with Fire” (1 to just under 2 weeks before travel), this zone was created for you. We added “Playing with Fire” this year, because the pricing is better than waiting until the very last minute. Booking here, you’re almost certainly going to pay more than “Prime Booking Window” shoppers and there’s going to be fewer flight options available. But if there’s good news it’s that you’re going to pay about 22% less on average than the people who wait even longer to buy in the next zone, Hail Mary.

Hail Mary

0-6 Days in Advance

(less than 1 week)

Oh dear. You waited this long to buy? We’re praying for you, dear traveler. Last-minute fares are considered the “Hail Mary” zone, so-named for obvious reasons – you’re likely to pay more (on average a whopping $208 more) than buying during the “Prime Booking” window, and you’ll surely face more limited choice in seats (oh, the dreaded center seat!).

The Days of the Week Angle

Much debate and confusion surrounds the dual topics of what day of week you should shop for flights and what day of week you should fly to get the best deals. We can break this down for you. It’s actually pretty simple.

Is there a cheapest day of the week to book flights?

Not really. The average lowest fares by purchase day of week are all within $2 of one another. That’s less than a 0.6% difference. That’s a negligible amount. Book any day of the week!

Is there a cheapest day of the week to fly?

Heck yes! Tuesday and Wednesday are the cheapest days to fly. Sunday is the most expensive. Flying on Wednesday instead of a Sunday will save you an average of $76 per airline ticket.

Seasonal Changes

Seasonality can also impact the best time to buy. Here’s the skinny on what to expect when booking flights for summer, fall, winter and spring.

When to Buy Summer Flights

Summer is the most popular season for Americans to travel. Do not wait until the last minute if you’re on a budget. In general, we recommend buying a bit earlier for the summer months, especially when traveling in July, which is the most popular air travel month of the season. August and September are where the best summer deals can be found, with late summer offering the lowest prices overall.

• The average best time to buy is 47 days, or about 1.5 months in advance.

• Prime Booking Window is 14 – 160 days (2 weeks to about 5 months) from travel.

• The difference between the best and worst priced days is $203

• Our summer airfare calendar can help make the shopping process simple and easy – showing you the cheapest and most expensive dates to fly.

When to Buy Flights in the Fall

Fall is a good value for leisure travel. It’s shoulder season for a lot of destinations, and most people have done their big trips in the summer. Therefore, you can usually find reasonably priced tickets in the fall. The one exception is Thanksgiving week, when airfares are priced at a premium and sell out quickly. You should definitely buy Thanksgiving airfare on the early side for the best prices.

• If you’re traveling in the fall (excluding Thanksgiving), you can usually wait a bit longer to book air tickets and still not miss out on the good prices. The best time to buy is 69 days out, a little over 2 months in advance.

• Prime Booking Window is 21 – 100 days from travel.

• The difference between the best and worst priced days is $83, a number that’s not nearly as painful as waiting to buy your tickets for any other season.

When to Buy Winter Flights

Christmas and New Years weeks can be a money pit, but otherwise winter is often a great time to get a good deal. For general (non-holiday) winter travel:

• 62 days from your expected travel date is the best time to buy an affordable airline ticket in the winter months.

• Prime Booking Window is 21 – 110 days from travel.

• The difference between the best and worst priced day is $260

When to Buy Spring Flights

Springtime is a bit tricky. On the one hand, there are no major travel holidays to drive up prices on specific dates. On the other hand, “spring break” dates cover March through April and inspire travel from college students and families with kids alike. So, in general, planning ahead is key for snagging better prices.

• Exactly 3 months (90 days) from your travel date on average is the optimal time to buy airfare for spring air travel.

• Prime Booking Window is 46 – 122 days from travel. Because you have a larger window to get the best fares, buying early is not a gamble.

• The difference between the best and worst priced day is $263.

Final Thoughts

If you take nothing else away from the 2018 Airfare Study, remember this: airfares change frequently. If you have an itinerary in mind, you must be ready to buy when you see a good fare. Going away to “think about it” is risky. Other travelers are also watching fares and someone else is likely to hop on a low fare while you’re mulling things over. Be decisive.

Another key finding is that purchasing during the “Prime Booking Window” can give you a clear edge and maximize your chances of scoring a cheap flight.

Check out our Best Time to Buy Flights search tool to research your destination and get custom advice from our airfare intelligence data. And if you find yourself in a bind (perhaps you need a last minute airfare, or you don’t have the budget in advance of your trip) consider our monthly payments option or what we call “Fly Now, Pay Later.” You can make installment payments for 3, 6 or 12 months – and not run the risk of losing that great fare!

Finally, if you’re thinking that this information would have been more helpful to you if we were focused on international destinations, we’ve got you covered there too! Our International When to Buy study is out and we break everything down for you international travelers!