How to find flights under 20 euros (without spending every evening on airline websites)

At a glance

• Flights under 20 euros really do exist, but almost never on the date and to the place you had in mind: you find them by starting from your budget, not your destination.
• The more flexible you are about dates, departure airport and destination, the more of them you'll find.
• The price you see is the base fare: bags, seats and airport check-in can multiply it. You can almost always avoid them.
• The best deals don't last long: it pays to get an alert rather than checking every evening.

1. Start from your budget, not your destination

Asking "how much is a flight to Paris on 12 March?" nearly always gets you a steep answer. The question that turns up flights under 20 euros is a different one: "where can I go in the next few months for less than 20 euros?"

Low-cost airlines fill their planes by dropping prices wherever seats are going empty: less popular routes, midweek days, off-peak periods. Leave the destination open and those are exactly the bargains that start to appear.

So search "anywhere", or across a whole country, with a price cap, and pick your destination from what comes up. Plenty of lesser-known cities in Poland, the Balkans or the Baltic states make brilliant trips precisely because they're so cheap to reach.

2. Be flexible with your dates

• Avoid peak periods: long weekends, public holidays, school holidays, high season and the weekends before Christmas are when low fares vanish first.
• Look at whole months, not single days: shifting your outbound or return by a single day can change the price by a surprising amount.
• Consider flying out and back midweek: if you can leave on a Tuesday or Wednesday, you'll usually have far more choice than on a Friday evening.
• Don't book too early or at the last minute: the lowest fares often show up a few weeks or a few months ahead; close to departure, the cheap seats have usually gone.

3. Widen your choice of departure airports

The nearest airport often isn't the cheapest, and many cities have more than one airport worth comparing: London has Stansted, Luton, Gatwick and Southend; Paris has Orly and Beauvais; Barcelona has El Prat, Girona and Reus; Milan has Malpensa, Linate and Bergamo; Brussels has Zaventem and Charleroi; Stockholm has Arlanda, Skavsta and Västerås. It works outside Europe too: in New York you can compare JFK, Newark and LaGuardia. An extra hour on the road can mean a flight at half the price, or a destination your own airport simply doesn't serve.

Do the maths on getting there, though: a 15-euro flight from a distant airport can cost more than a 30-euro one on your doorstep if the bus or parking costs 20. Check where the airport really is, too: some airports named after a big city are more than an hour from its centre.

4. Combine two one-way flights

Your outbound and return don't have to be with the same airline, or even leave from and land at the same airport. Two cheap one-way flights often beat a return ticket.

You can also fly into one city and out of another: for instance, land in Vilnius, take the bus to Riga and Tallinn, then fly home from Vilnius or another well-connected city. It's the cheapest way to see several places in a single trip.

Watch out: if you book two separate flights, a delay on the first one doesn't entitle you to be rebooked on the second. Always leave a generous gap between flights, ideally a night.

5. Don't let extras eat up your savings

A low-cost airline's base fare usually includes only a small bag that fits under the seat. Everything else costs extra. Here's how to keep the price down:

• Travel with just the small bag: it's plenty for a weekend. Permitted sizes vary between airlines and get updated, so check them on the website before you go: there's little tolerance at the gate and the fees are steep.
• Check in online: some airlines charge for checking in at the airport.
• Skip seat selection: unless you need to sit next to someone, a randomly assigned seat is free.
• Read the summary before you pay: insurance, car hire and other add-ons may already be ticked for you.
• Compare the final total, not the headline price: that's what you actually pay.

6. Get alerts instead of searching every evening

Low-cost fares change constantly, sometimes several times a day, and the cheapest ones don't stick around. Manually checking every route from two or three airports across months of dates just isn't realistic.

The answer is a price alert: set your airports, dates and budget once, and get a notification when a flight that matches your rules appears. That's exactly what FlyDown was built for, and it goes a step further by showing you cities near your destination too, with the bus connections already worked out.

7. Two myths

• "If you search the same flight repeatedly, the price goes up": there's no solid evidence for this. More often the price rises because the cheap seats on that flight are selling out, regardless of who's searching.
• "Tuesday is the best day to book": when you fly (midweek, low season) matters far more than the day you book.

In short

1. Set your budget and leave the destination open.
2. Look at whole months and avoid long weekends and high season.
3. Widen your departure airports, factoring in the cost of getting there.
4. Combine one-way flights and, if you fancy it, visit several cities in the same trip.
5. Travel light and check the total before you pay.
6. Set an alert and let the deals find you.