When to Book Flights for the Lowest Fares: A Practical Guide

Is it cheaper to book on a Tuesday? Do prices go up every time you search for the same flight? There's plenty of advice about the "magic moment" to book flights, but most of it is outdated or simply wrong.

The truth is simpler: the price of a ticket depends mainly on the date you fly, how many people want to fly that day, and how many cheap seats are left on the flight. This guide explains how to use those factors to pay less.

Why do flight prices keep changing?

Airlines split the seats on every flight into fare levels. The cheapest seats are limited, and once they're sold, the price moves up to the next level. That's why you can see one price today and a higher one tomorrow, with nothing changed except that some seats have been sold.

Airlines also adjust fares to demand, which depends on several things:

• The season: summer, school holidays, Christmas and New Year, Easter, and major festivals and religious holidays.
• The day you fly: flights at the start and end of the weekend usually cost more than midweek flights.
• Competition on the route: routes served by several airlines, especially low-cost ones, tend to have better fares.
• Time left before departure: the closer the flight and the fuller the plane, the higher the price, most of the time.

Common myths about booking flights

"Booking on a Tuesday is cheaper"

This advice dates from the days when airlines updated their fares manually on set days. Today, prices change automatically all the time, and any difference between booking days is tiny compared with the difference between travel days.

"Prices go up because you searched too often"

There's no strong evidence that booking sites raise prices because of your repeated searches. What usually happens is that the cheapest seats sold out between searches, or the price you saw earlier was no longer up to date. Don't put off booking in the hope of a trick that won't change the price.

"Last-minute deals are the cheapest"

That's sometimes true for hotels and package holidays, but rarely for flights. On most routes, fares rise noticeably in the last two weeks before departure, because people who book late are usually people who have to travel.

How far ahead should you book? Rough rules by type of trip

Every route is different, but these general rules are a good starting point:

Your travel date matters more than your booking date

If your plans are flexible, this is your biggest chance to save. The price calendar makes the difference plain: from New York to London, the cheapest round trip in February started at $404, while in June it was $801, almost twice as much. Try these:

• Move your trip by two or three days: a small change to your outbound or return date can change the price a lot.
• Fly midweek: Tuesday and Wednesday flights are usually cheaper than flights at the start or end of the weekend.
• Try different departure times: early-morning and late-night flights can be cheaper than flights in the middle of the day.
• Avoid the first and last days of holidays: the first and last days of public and school holidays are among the most expensive days to fly.
• Change the length of your stay: a one-week trip can be priced differently from a ten-day or two-week trip, so compare more than one length.

How to find the cheapest month and day with a price calendar

Instead of searching each date one by one, a price calendar shows you the lowest fare found for every month of the year at a glance. Try it now:

1. Choose your departure city and destination. Our example is London to New York; you can change both cities from the settings icon at the top of the calendar.
2. Look at the months. The calendar highlights the cheapest month, so you can see straight away when your trip costs least. On this route, February started at $406, against $715 in July.
3. Open the month that suits you to compare prices day by day, and pick the cheapest days to fly out and back.
4. Go to the search results to see every offer for your dates from airlines and travel agencies, then book directly with the seller you choose.

More ways to bring the price down

• Compare nearby airports: some cities are served by more than one airport, and another airport within reasonable reach may have lower fares.
• Compare a round trip with two one-way tickets: sometimes flying out with one airline and back with another is cheaper, and sometimes it costs far more. We compared both on 13 routes in round trip or two one-way tickets?
• Work out the full price, not the headline fare: some cheap tickets, especially with low-cost airlines, don't include checked bags or seat selection. Add those costs before you compare, as we explain in the real cost of a cheap flight.
• Check the seller before you pay: TravelFlow shows fares from different airlines and travel agencies. Read the ticket's change and cancellation rules, and the seller's reviews, before you complete your booking.
• Watch the price for a few days: if your trip is a long way off, check the fare every few days to get a feel for its usual level, so you'll recognize a good deal when it appears.

The bottom line: a 5-step plan before any booking

1. Decide what kind of trip it is, and start comparing at the right time using the table above.
2. Use the price calendar to find the cheapest month, then the cheapest day.
3. Be flexible by two or three days on your outbound and return dates.
4. Compare the full price including bags, not just the headline fare.
5. Book when you find a good fare, especially in peak season, and don't wait for a magic day that will never come.