Best Time to Book Flights: How Far Ahead, by Trip Type (2026 Data)

Other 2026 studies give shorter windows partly because they measure something else: Google tracks fares on offer over time, Kayak averages search results, and Expedia averages the tickets people actually bought.

Key facts (checked 8 November 2026)

• Domestic: Google Flights 2026: lowest prices 39 days out, low range 22–57 days. Kayak 2026: 21–30 days. Expedia 2026: 15–30 days.
• International: Google Flights 2026: lowest at 89 days, but prices barely move between 50 and 133 days, so book "as soon as you can". Kayak and Expedia found their lowest averages 1–2 weeks out; treat that with caution (see below).
• Holidays (Google 2026): Thanksgiving 21–57 days ahead, Christmas 33–67 days, summer (July–August) 20–47 days.
• Last minute rarely pays for domestic trips. Hopper (January 2025) says domestic prices "can increase by almost double in the last 3 weeks". Airline sale fares usually need advance purchase: Southwest's 27 October 2026 sale required 21 days.
• The day you book barely matters: Google's 2026 data put the best booking day about 1.4% below the worst. The day you fly matters more.

What each study says about how far ahead to book

For domestic trips the studies agree that booking six months or more ahead and booking in the final days both cost more. They disagree on where the cheap window sits, especially for international trips. We read each publisher's own page on 8 November 2026; the table is newest first.

The "1 to 3 months" and "2 to 8 months" you see in many answers come from Going's guidance as repeated by NerdWallet (Going adds 1–2 months for peak seasons). Going publishes no method, so treat those ranges as rules of thumb rather than measurements.

Why the studies disagree

The studies measure different things over different periods.

• Fares on offer vs tickets bought. Google reports average fares "relative to the departure date" for defined trip types (in 2025: 4- to 16-day round trips). Expedia averages the tickets its customers actually bought in each window, so its 8–15-day international figure also reflects which trips people buy late. Expedia does not say whether those trips are comparable with the ones booked months ahead.
• Where the measurement stops. Kayak only looked at searches 7 to 183 days before departure. Its cheapest international window, 7–14 days, sits at the edge of what it measured, so the data cannot show whether the last week was cheaper or dearer.
• Lowest point vs low range. Google's single "lowest" day (89 days for international trips) sits inside a long flat range. In Google's own words, "the average price drop during the low range (50–133 days out) is insignificant". A range is the more useful number.
• Different years. Expedia 2026 uses bookings from December 2024 to November 2025, Kayak searches from January 2025 to March 2026, and Google averages five years. CheapAir's newest studies are from 2024; we found no 2025 or 2026 edition.
• Different routes. CheapAir's 2024 regional spread (29 days for the Caribbean, 320 for Europe) shows what a single "international" number hides.

If your dates are fixed, Google's 2026 advice is the safe default: "When your dates are already set, booking early is the safest bet to protect your itinerary."

How far in advance should you book a domestic flight?

Aim for 3 to 8 weeks before departure, Google's 2026 low-price range. The other two 2026 datasets point to the final month before departure (Kayak 21–30 days, Expedia 15–30 days).

Booking much earlier does not help. Expedia's 2026 report found domestic economy tickets bought 15–30 days out averaged $130 less than those bought more than six months out, and the report's advice was "Book closer than you think — but not last‑minute". Booking much later is the bigger risk. Hopper's 2025 guidance is to "expect to book 1-2 months ahead" and warns that prices "can increase by almost double in the last 3 weeks ahead of takeoff".

If you book seven days or more before departure, US rules give you a free safety net. Airlines must either let you hold the fare without payment or let you cancel without penalty for at least 24 hours (14 CFR 259.5(b)(4)). The airline picks which of the two it offers, and the DOT says the rule does not apply to tickets booked through travel agents or online travel agencies; our guide to US refund rights when flights are cancelled or changed covers what you are owed later.

Which day of the week you fly is a separate lever; the datasets on that are compared in our guide to the cheapest day to fly.

How far in advance should you book an international flight?

Book international trips about 1½ to 4 months ahead, and earlier rather than later. That is Google's 2026 low-price range, and its advice is: "For trips abroad, you should try to book as soon as you can!"

Region changes the answer:

• Europe: lowest prices about 90 days out, and "waiting rarely pays off"; the low range is 49 days or more before departure (Google, 2026).
• Mexico and the Caribbean: lowest prices 43 days out, low range 24–69 days, much closer to departure than Europe (Google, 2026).
• Asia and Oceania: Hopper's 2025 guidance is to book 5–7 months ahead; other regions 3–6 months.

The short windows in Kayak (7–14 days) and Expedia (8–15 days) are averages across all international trips. Neither publisher splits that figure by region or tracks the same transatlantic trip over time, so do not plan a long-haul trip around them. Kayak itself calls its result "a bit of a surprise" and adds "Proceed with caution!"

When should you book Thanksgiving, Christmas and summer flights?

Holiday windows differ from the yearly average: Christmas sits earlier, summer later. In Google's 2026 analysis, Thanksgiving fares were lowest 34 days before departure, Christmas fares 56 days before, and July–August trips 21 days before. Google's summary for 2026: "October is when Thanksgiving flights tend to be cheapest", and the Christmas sweet spot "has shifted even earlier".

Google publishes these windows every autumn, so you can see how much they move from year to year (days before departure; lowest point, then low range):

Google published its method in 2024 and 2025 but not in 2026. In 2025 it used round-trip fares observed 1 January 2021 to 1 August 2025 for 4- to 16-day trips from the top 4,000 US markets, counting holiday trips that leave before the holiday and return after it. In 2024 it used 6- to 9-day and 13- to 16-day trips, so the columns are not measured in exactly the same way.

Here is what the 2026 windows mean in calendar dates. This is our arithmetic, assuming the 2026 day counts hold:

For Christmas 2026, Google's low range ends on 19 November, so the dates you fly now matter more than waiting. Hopper found the Monday or Tuesday before Christmas cheapest (about $440), the weekend of 18–20 December most expensive, and Sunday 27 December returns about 20% dearer than early-week returns. Its 2026 Holiday Travel Index (September 2026) had told travelers to "expect to book flights and hotel stays before Halloween", with domestic Christmas round trips already averaging $452, up 23% on 2025.

Which months are cheapest to fly?

August is the cheapest month to fly overall and January the cheapest for domestic trips, according to Expedia's 2026 report: August fares were 29% (about $120 a ticket) below December, and January domestic fares 19% below December. The month you travel moves the price more than the day you book; the report puts it as "When you fly matters more than when you book". The cheapest month to book was July, 18% below December. For trips abroad, CheapAir's 2024 international study named February "the most cost-effective month for international travel (region dependent)".

Do flights get cheaper last minute?

Usually not for domestic trips. Every recent domestic window ends at least two weeks before departure (Google 22 days, Kayak 21, Expedia 15), and Expedia and ARC's 2025 report found that booking domestic flights at least 34 days out saved up to 25% compared with last-minute bookings. Kayak explains why: on business routes and in premium cabins prices tend to rise as departure approaches, because "corporate travelers, who tend to book closer to their trips, scramble to get a remaining seat".

The exception is leisure travel: Kayak says falling prices close to departure are "more common in economy class cabins and on leisure travel routes". Summer is the one peak that tolerates waiting, since Google's 2026 July–August low range runs to 20 days before departure, about three weeks. For international trips, Kayak and Expedia found their lowest averages one to two weeks out, with the caveats above.

What the airlines' own sale pages offer

Airline sale fares are real discounts, but they are usually not last-minute fares. These are the official pages, checked on 8 November 2026:

• Southwest: the Flight Deals and Offers page, the lowest-fares search and the Low Fare Calendar. Southwest says the fares on its deals search "have been collected within the last 24 hours and may no longer be available" and are Basic fares, which pay for checked bags (Southwest's bag fees by fare). Its national sale of 27–29 October 2026 required a "21-day advance purchase" and blacked out dates around Thanksgiving, Christmas and New Year.
• United: the Weekly Deals page lists domestic and international round trips. Most of its sections say the fares listed are Basic Economy, which United says means no free seat selection, "no full-sized carry-on bags and no flight changes or refunds except as stated in the United 24-hour flexible booking policy"; see United's cancellation and Basic Economy rules.

When last-minute booking makes sense

• You are flexible on where you go. Deal pages help most when you can pick whichever destination is cheap that week.
• You fly a leisure route off-peak. That is where Kayak sees prices drop close to departure; holiday weeks are the opposite.
• You fly a budget airline. Going's myth guide (updated 23 October 2024) says budget carriers "occasionally have good deals on last-minute flights", because few business travelers use them. Compare the total with bags: US budget airlines' fees side by side.

Know what you give up. A booking made less than seven days before departure is not covered by the federal 24-hour hold-or-cancel rule, which applies only to reservations made "one week or more prior to a flight's departure". In a last-minute rush, book on the airline's site or app, never through a phone number from an ad or a search result: how fake airline helplines work.

How to time your booking: five steps

1. Pick your window from the sections above: domestic, international (earlier for Asia and Oceania) or the Google holiday rows.
2. Start watching early. Kayak suggests setting price alerts "2-4 months before your intended travel dates". For your exact route and dates, Google Flights shows how current prices compare with prior years and "whether they're likely to go up or down".
3. Book when the fare fits your budget inside the window. Kayak's advice: "waiting for a lower fare that may never come can backfire."
4. Use the 24-hour rule. Booked directly with the airline at least a week ahead? The hold or free cancellation described above lets you lock a fare and still rebook if a better one appears within 24 hours.
5. Keep checking after you book, unless it is Basic Economy. Booked through an agency? Its rules apply.

• United's change rules vary by fare; check the current fare rules before rebooking.
• Delta says it eliminated change fees for tickets originating in the U.S. or Canada for Classic and Extra experiences; Basic tickets may carry a change fee. If the replacement flight costs more, you pay the fare difference. If it costs less, Delta says the difference "will be issued to you as a Delta eCredit".
• Basic Economy restrictions vary by airline. American says its "Basic Economy fare tickets cannot be changed", with a few exceptions (American's Basic Economy and refund rules).

Why booking-window advice differs

We compared widely repeated booking-window claims with the studies they rely on. Jettly’s May 2026 guide presents several different international booking windows, including 2–8 months and 50–101 days. We distinguish each dataset rather than treating one window as universal.

How we checked

On 8 November 2026 we read every study in the tables on its publisher's own page and took each number from there. We read Expedia’s 17 February 2026 release on Expedia’s newsroom on 8 November 2026. Southwest's, United's, Delta's and American's deal, sale and change-policy pages were read the same day. We did not collect our own fare data for this edition; if we add a fare panel, it will show its routes, dates and method.

We update this page in early January, again when Expedia and Kayak publish new data (February and March in 2026), and each autumn when Google publishes its holiday analysis.

Common questions

How far in advance can you book a flight?

At the big US airlines, usually about 11 months. Going (October 2026) says American, Delta and United "open bookings up to 11 months in advance", roughly 330 days; the airlines' own pages we could read give no day count, so the last date in the airline's booking calendar is the real limit. Check Southwest’s published schedule before planning around a future departure; its booking horizon can differ from those of other major U.S. airlines. For domestic trips, booking that early does not get the lowest fare in any study above.

Is 6 months in advance too early to book a flight?

For a domestic flight, usually yes. Expedia's 2026 report found domestic tickets bought more than 180 days out were the most expensive, $130 more on average than those bought 15–30 days out. For some long-haul trips it is not too early: Hopper's 2025 guidance is 5–7 months for Asia and Oceania, and CheapAir's 2024 study put the best Europe window even earlier, 320 days out. Google's 2026 international low range, by contrast, ends at 133 days.

Is Tuesday still the cheapest day to book a flight?

No. Google's 2026 analysis found Wednesday the cheapest day to book, but only about 1.4% below Sunday, and Kayak calls the Tuesday theory "simply not true". According to Going, the belief dates from when airlines posted new fares by hand, "often Tuesdays at 1pm".

Do flight prices go up if you keep searching?

We found no evidence that they do. A KU Leuven and Inria study ran more than 130,000 searches on 25 airlines' websites over three weeks in 2014, with and without cookies, and found no "evidence for systematic price discrimination". Going (2024) lists likelier causes of a higher second price: the fare changed, the cheaper seats sold, or a booking site was showing an out-of-date fare. Clearing cookies or using incognito mode is harmless, but neither source found that it gets you a lower fare.

Do flight prices drop at 3am?

Not on a schedule. Kayak's answer to whether prices go down at night is "Sometimes": fares are updated by software, which "can certainly happen at night, but it is equally like[ly] to happen any time of day, any day of the week". Kayak says prices can change several times a day.

Should I book now or wait for prices to drop?

If your dates are fixed and you are inside the window for your trip, book. Google's 2026 advice is that booking early "is the safest bet to protect your itinerary". On a standard Economy ticket with United you can still switch to a cheaper flight later without a change fee and keep the difference as travel credit (step 5 above). If you are still months out, set a price alert and decide once you reach the window.