How we know: Sources are listed at the end. Booking-window figures come from Google Flights and ARC/Expedia's published analyses of their own data; Wildly does not have a fare history of its own to draw on yet.
"Book now or wait" is a bet with an asymmetric payoff. If you wait and the fare drops, you save a modest amount. If you wait and it rises, you can pay a lot more or lose the trip. So the question is not "could it get cheaper" (it always could) but "am I inside the window where waiting usually pays, and can I afford to be wrong?"
Four questions that decide it
1. How far out are you? Google Flights' price history puts the typical low for domestic US fares at 21–52 days before departure, for US–Europe around 94 days out (low range 50+ days), and for Mexico and the Caribbean 26–68 days out (Thrifty Traveler on Google Flights data). If you are well before those windows, waiting is reasonable. If you are inside or past them, the odds shift toward booking.
2. Are your dates flexible by a day or two? Flexibility is what makes waiting safe: if your preferred date rises you can move. With fixed dates, every week closer to departure removes options.
3. Is it a peak date? Summer Europe, the December holidays, spring break, and destination events price early and rarely fall. For Thanksgiving and Christmas the Google data shows the low points about 45 and 58 days out respectively; after that, fares mostly climb.
4. Would a moderate increase hurt? If a couple of hundred dollars more would break the budget or cancel the trip, take the acceptable fare in front of you. Regret over a slightly cheaper fare you missed is cheap; regret over a trip you did not take is not.
If you answered "well before the window", "flexible", "off-peak" and "an increase would be fine", waiting is a sensible bet. Two or more answers in the other direction: book.
Warning signs that prices are about to rise
- Seat maps filling up. Airlines sell from cheaper fare buckets first; when a flight is filling, the cheaper buckets close and the displayed price steps up.
- You are inside three weeks of departure. Late bookings skew toward business and must-go travel, and prices reflect that.
- A major event has been announced at your destination for your dates (a festival, a sporting final, a conference). Demand moves before you do.
- Google's tracker is warning you. Google Flights' price tracking sends notices when "prices for a route you track are likely to go up", with an estimate of how much (Google Flights Help). Treat that as one input, not a guarantee.
When waiting genuinely pays
- You are months ahead of the typical low window for your route type.
- You are travelling off-peak to a leisure destination with lots of competing flights.
- You can move dates, or even airports, to catch a cheaper option.
- You are watching the route with an alert so you do not have to keep checking.
ARC and Expedia's ticketing data illustrates the upside: international travellers who booked 18–29 days before departure saved up to 17% compared with those who booked more than two months out (ARC / Expedia 2025 Air Hacks). That is an average across many travellers, and the same dataset shows plenty of late bookers paid more, which is exactly why flexibility is the condition for waiting.
Take the decision out of your hands
Decide today what price you would be happy to pay, then set a price alert at that number on the route you care about, such as JFK to Paris, San Francisco to Tokyo or LAX to London. Wildly checks the fare daily and emails you when it crosses your target. If it never does and you are approaching the booking window, book at the going rate; you have lost nothing by waiting with an alert running. For how to choose the number, see setting the right price alert target.
Refundable fares and free changes
Most US carriers now let you change many main-cabin tickets without a change fee (you pay any fare difference), and some hold or "freeze" options exist. If a fare is acceptable but you suspect it might fall, booking a changeable fare and rebooking on a drop is often better than waiting empty-handed. Check the fare rules before you rely on this; basic economy is usually excluded.
FAQ
Do flight prices go down closer to the date? Sometimes on off-peak leisure routes; rarely on peak dates or business-heavy routes. On average, fares inside the final three weeks are higher.
Is it cheaper to book last minute? For most trips, no. Last-minute bargains exist but are unpredictable, and the downside when they do not appear is large.
How long should I track before booking? Until you reach the typical low window for your route type. If you are already inside it and the fare is acceptable, book.