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When to book low-cost flights to pay less: what the data really says

How far ahead to book, whether the day of the week matters, and how prices at Ryanair, Wizz Air, easyJet and other budget airlines change in peak season and at the last minute. With sources, and no myths.

Updated on 18 September 2026

The month's calendar in an open planner, with a highlighter
Photo: Estée Janssens · Unsplash

At a glance

  • There's no magic day that works for everyone: serious studies give different windows, and partly contradict each other.
  • On budget airlines the price rises as seats sell: in the last few days before departure it usually costs a lot more.
  • For the busiest dates (summer, Christmas, Easter, school holidays, long weekends) it pays to act earlier; in the off-season you have more room.
  • The day you book matters very little. The day and the period you fly matter far more.
  • The best deals appear and vanish quickly: rather than guessing the moment, you need to notice them.

How low-cost airlines set their prices

Ryanair, Wizz Air, easyJet, Vueling, Volotea and Transavia use dynamic pricing: each flight has a number of seats sold at rising prices, in tiers. When the cheapest tier runs out, the price moves up to the next one. If a flight fills more slowly than expected, the price can also drop.

A study by Alderighi, Nicolini and Piga on Ryanair data measured exactly this: each extra seat sold on a flight was linked to an average fare increase of about 3%. In the same study, prices tended to fall slightly until about ten days before take-off, then jumped sharply, by 50-75%, in the final days. The data is a few years old, though: treat it as a description of the mechanism, not a precise calendar.

Another piece of research on Ryanair (Malighetti, Paleari and Redondi) found that where there's more competition, discounts for booking early are bigger. In plain terms: routes served by several airlines offer more opportunities.

How far ahead to book: what the studies say

Here are the most quoted figures. Note that nearly all of them come from the US market or from tickets sold through agencies, not from the websites of European budget airlines: they're useful clues, not rules.

SourceWhat it measuredWhat it found
Alderighi, Nicolini, PigaRyanair faresPrices falling slightly until about 10 days before, then steep rises in the final days
Google Flights (2022)5 years of prices, mostly from the United StatesMinimal difference between booking days; flights departing Monday to Wednesday cheaper than weekend ones
Kayak (2026)Searches on kayak.com, 2025-2026"Tuesday is cheapest" isn't true; findings on how far ahead to book vary a lot by type of trip
Expedia and ARC (2026)Tickets sold through agenciesFor international flights, booking within about 45 days beats booking six months out; the booking day is worth only a few percentage points
Which? (2025)Official UK flight price dataAugust flights cost far more on average than January ones, and the gap has grown since the pandemic

As you can see, the "ideal" windows don't line up: some point to a few weeks, others to a few months. What they all agree on is something else: booking too close to departure costs more, and at peak times the cheap seats run out sooner.

A practical rule for budget airlines

  • Off-season, flexible dates: there's no need to book months ahead. Keep an eye on prices from a few months before and buy when you find a fare within your budget.
  • Peak season and holidays: summer, Christmas, New Year, Easter and school holidays fill up early. Waiting rarely pays off here: start looking when the season's schedules come out.
  • Last minute: a half-empty flight may get a price drop, but that's the exception. As a rule, only the most expensive tiers are left in the final days.
  • Don't hold out for the "perfect" price: if a fare works for you, it's a good price. Waiting longer often means finding only higher fares.

Seasons, holidays and long weekends

A wall calendar with a few dates marked with pins
Photo: Towfiqu barbhuiya · Unsplash

The biggest factor in the price isn't when you book, but when you fly. According to the British consumer group Which?, which analysed official UK data, August flights cost far more on average than January ones, and the gap with the quiet months has widened in recent years.

  • The quietest months for short flights in Europe are usually January, November and March (outside Easter), according to the same analysis.
  • September beats June and August for many beach destinations: it's still warm and demand drops.
  • School holidays vary from country to country, and sometimes from region to region. A destination can be very expensive while locals are on holiday and quiet a week later.
  • Long weekends and public holidays push up prices both from your airport and towards the country celebrating them: check both calendars.
  • Your departure day matters: midweek flights often cost less than Friday and Sunday ones.

Myths about the right moment

  • "Tickets are cheaper on Tuesdays": Google Flights found differences below 2% between booking days, and Kayak calls it simply untrue. Expedia's research names a different day every year, always with small differences.
  • "If you search many times, the price goes up for you": a European Commission study using simulated purchases found no evidence of systematic personalised pricing. Prices change often because seats sell, not because you've been recognised.
  • "The earlier you book, the less you pay, always": not so. In the Ryanair data prices could fall slightly in the weeks before departure, and some studies find the lowest point just a few weeks before the flight.

Flash sales and seat sales

Budget airlines regularly launch time-limited deals, often lasting a day or two, with no warning. Sometimes they cover dates far ahead, other times they're meant to fill flights that are selling slowly. They're worth knowing about, but don't count on them: you don't know when they'll come or on which routes.

Since prices change all the time and cheap seats don't last, the most reliable method isn't guessing the right day but getting alerted. With FlyDown you set up a watch with airports, dates and budget, and you get a notification when a flight drops below the amount you chose.

In summary

  1. Avoid booking in the final days: on budget airlines it's almost always the most expensive choice.
  2. For summer, holidays and school breaks, move early.
  3. In the off-season you have time: watch prices and decide calmly.
  4. Forget the day of the week you book; choose the day you fly wisely.
  5. Set your budget first and buy when the price fits.
  6. Set up a watch, so flash sales don't slip past you.

Sources

Sources consulted in September 2026. FlyDown is not affiliated with the airlines mentioned: trademarks belong to their respective owners.