How we know: Sources are listed at the end. Every booking-window figure below is quoted from the named publisher's analysis of its own data (Google Flights, ARC/Expedia, Hopper); none of it is a Wildly measurement.
There is no single "book X weeks out" rule. The published studies disagree with each other because they measure different things (average fare paid vs. lowest fare available, domestic vs. international, ordinary weeks vs. holidays). Read together, though, they agree on the shape: book earlier for long-haul and peak dates, later for domestic and short-haul, and ignore the day of the week you buy.
What the published data says
Google Flights (analysis of its own price history, summarised by Thrifty Traveler). Domestic US fares have been lowest 21–52 days before travel, with the average low point at 38 days out. Flights from the US to Europe have been cheapest around 94 days before departure, with the low range starting 50 days or more out. Mexico and Caribbean fares have been lowest 26–68 days before departure, with 44 days the average low. For Thanksgiving the low range was 26–59 days out (about 45 on average); for domestic Christmas travel, 36–72 days out (about 58 on average). (Thrifty Traveler on Google Flights data)
ARC / Expedia (ticketing data). Travellers who booked international flights 18 to 29 days before departure saved up to 17% compared with those who booked more than two months out; Sunday was the cheapest day to buy, by up to 8% versus Friday; and for international trips, departing on a Thursday saved up to 15% compared with Sunday. (ARC / Expedia 2025 Air Hacks)
Hopper (quoted by The Points Guy). Hopper's economist recommends booking Europe and most international regions three to six months out, and transpacific trips to Asia and Oceania five to seven months out; The Points Guy's own guidance is one to two months for domestic and three to five for international. (The Points Guy)
Why do Google and ARC disagree on international timing? Google reports when the lowest available fare tends to appear; ARC reports what people actually paid on average. Late bookers who found a bargain pull the ARC average down, but plenty of late bookers paid a lot. Treat the earlier windows as the safe plan and the later ones as an opportunity, not a strategy.
A practical schedule by route type
- Domestic US: start watching two to three months out; expect the best prices somewhere in the one-to-two-month window. Inside two weeks, prices usually climb.
- Transatlantic (US to Europe): start watching four to six months out. For summer and Christmas, book once you see a fare you would be happy with in the three-month window; for shoulder and winter travel there is more room to wait.
- Transpacific and Australia/New Zealand: long-haul routes with fewer competitors discount less close to departure. Hopper's five-to-seven-month guidance is the conservative play, especially for peak dates such as cherry-blossom season or the December holidays.
- Mexico, Central America, Caribbean: leisure-driven and seasonal. Google's 26–68-day window is a reasonable target outside spring break and the winter holidays; for those dates, add a month or two.
- Holidays (Thanksgiving, Christmas, spring break): use the holiday-specific windows above and do not wait for a last-minute drop. Midweek departures around a holiday are consistently cheaper than the peak travel days.
Live prices for the busiest routes are on the route pages, for example JFK to Paris, LAX to London, San Francisco to Tokyo and Chicago to Cancún.
Day of the week: buying vs. flying
Buying on a Tuesday does not matter much. In Google Flights' data the cheapest day of the week to book was only about 1.3% cheaper than the most expensive (Sunday), while flying midweek (Monday to Wednesday) was about 13% cheaper than flying Friday to Sunday (Thrifty Traveler on Google Flights data). ARC's ticketing data points the other way on purchase day (Sunday cheapest) but agrees that departure day matters more. Spend your flexibility on when you fly, not when you click buy.
Time of day and repeated searching
Airlines update fares continuously through their revenue-management systems; there is no reliable hour when prices are lowest for a shopper. Searching the same route ten times a day does not surface a lower fare, it just uses up your attention. If your dates are fixed, decide your acceptable price, set a price alert, and let the check run daily. Wildly checks the routes you track every day (twice daily on Pro) and emails you when the fare falls below your target.
When last-minute can work
Last-minute bargains are most plausible on leisure routes in the off-season with more seats than demand, and least plausible on business-heavy routes or any peak date. If you must travel (a wedding, a conference), book inside the recommended window and stop looking. If you are genuinely flexible on destination and dates, a late deal can appear; a stretch-price alert on a few routes is the low-effort way to catch one.
Mistake fares
Genuine pricing errors do happen and can be extraordinary, but they cannot be predicted or planned around. Book immediately if one appears, wait for the ticket to be issued before booking anything non-refundable around it, and treat it as a bonus rather than a strategy. See our error fares guide.
FAQ
How far in advance should I book an international flight? For Europe, the published low point is roughly three months out (Google Flights), with Hopper recommending three to six months; for Asia and Oceania, five to seven months for peak dates. If you see a fare you like inside those windows, take it.
Is it cheaper to book on Tuesday? Not meaningfully. Google Flights' data puts the day-of-week booking difference at about 1.3%. Flying midweek matters far more.
Do prices drop right before departure? Sometimes, on off-peak leisure routes; rarely on peak dates or business routes. Do not count on it for a trip you have to take.
What is the cheapest month to fly? It depends on the destination's demand calendar. See best months to fly for a season-by-season view.