The standard city break model is return flights: fly in, fly out of the same airport. It's simple and usually the cheapest option. But if your itinerary covers two cities, or you want to avoid backtracking, a multi-city or open-jaw flight changes the economics significantly.

Here's how it works and when it's worth it.

What Is an Open-Jaw Flight?

An open-jaw ticket lets you fly into one city and out of another. For example: London to Paris outbound, Barcelona to London return. You travel between Paris and Barcelona by train, bus, or internal flight.

This is different from a multi-city booking, which adds a third (or fourth) leg. Both types are standard bookings, not travel hacks, and most major airlines and booking platforms support them.

When an Open-Jaw Makes Obvious Sense

Linear routes. If you're planning a trip through France, Spain, or Italy where the cities are in a geographic sequence, flying in at one end and out at the other eliminates backtracking. Paris to Barcelona by train, then fly home from Barcelona, is cheaper and faster than returning to Paris for the return flight.

City pairs with expensive or slow connections. If getting between two cities by train or bus takes more than 4-5 hours, an internal flight combined with open-jaw routing can save significant time.

Avoiding deadhead returns. Returning to your starting city just to fly home wastes half a day. An open-jaw removes this.

How to Search and Book

Google Flights: The most useful starting point. Use the multi-city search function (not the return option) to enter your outbound and return airports separately. It aggregates routes across airlines and gives you a clear price comparison.

Skyscanner: Has a solid multi-city search and sometimes surfaces budget airline fares that Google Flights misses.

Direct with airlines: If your itinerary is within a single airline's network (BA, Lufthansa, KLM), booking direct can be marginally cheaper and avoids third-party booking complications if something goes wrong.

Separate tickets: Sometimes booking two one-way tickets is cheaper than an open-jaw. Always check. The risk is that if your outbound flight is delayed and you miss your return, the airline is not responsible when the tickets are separate. Factor that in.

The Train vs Fly Decision

For the connecting leg between cities, train is usually better under 3-4 hours:

  • Paris to Brussels: 1h22 by Eurostar/Thalys. No contest.
  • Paris to Barcelona: 6h30 by TGV. A borderline call depending on your time and budget.
  • Amsterdam to Berlin: 6h by train, but overnight options change the calculation.
  • Rome to Naples: 1h10 by high-speed train. Absolutely take the train.

For anything over 4 hours, an internal flight may be worth considering, especially with budget carriers like Vueling, Transavia, or Ryanair.

Common Mistakes

Not leaving enough time between legs. If you're booking separate tickets for the connecting leg, allow at least a full day's buffer. A train to catch a flight with a 2-hour window is not a plan, it's a gamble.

Ignoring luggage rules. If you connect between airlines, check-in baggage policies may differ. Ryanair's cabin bag rules do not apply to your BA return ticket. This matters if you're travelling light.

Booking the return first. When prices fluctuate, sometimes booking the outbound first and checking the return on a separate search gets you to a lower overall price than booking both in one session. Not always, but worth checking.

The Tools Worth Using

Google Flights' price calendar view is the best way to find the cheapest days for each leg. Build your open-jaw search, switch to calendar view, and compare costs across a week either side of your planned dates. Even a one-day shift can save £40-80 per person on popular routes.