- Every flight leg is searched twice: the normal search, plus a second search with the airline layover filter set to your minimum (10 hours by default; anywhere from 4 to 24 in Advanced). The two result sets are merged and deduplicated by flight number and price.
- Each itinerary's connections are read out. A connection counts only if it meets your minimum and the city is not your origin, your destination or your home city.
- A layover in your own country is not a free city unless you specifically asked for that city.
- Every candidate is priced two ways: against the cheapest fare on that leg, and against buying it as two separate flights (A to the layover city, then the layover city to B the next day).
- It is kept when it costs no more than $60, or 15% of the leg fare, above the cheapest option — whichever is larger. A city you actually asked for is kept even above that, as long as it beats booking two tickets.
- Consecutive legs get a pair check: is there one A → C ticket with a long connection in B that beats your separate A → B and B → C legs? When there is, it replaces both.
- Each result is measured against a table of minimum useful hours per airport — Istanbul 8, Heathrow 6, Charles de Gaulle 7, Beauvais 9, Singapore 4 — so the plan can tell you whether the stop is long enough to be worth leaving for.
- Ticket
- DFW → LHR via Madrid on Iberia, one booking
- Fare
- $533 per person
- Versus the cheapest way to fly that leg
- $43 more
- Versus buying Dallas → Madrid → London as two tickets
- $199 less
- Time in Madrid
- 25 hours: an evening, a night and a full day
Madrid was already on the list, so one ticket can stand in for a separate leg later in the trip. The same run found a second one: 29.7 hours in Budapest on the Athens → Rome ticket, $20 above the cheapest fare on that leg.
A dozen airlines will let you break the journey at their hub for days rather than hours, with no change in airfare, and some will pay for the hotel. Every carrier and hub on your plan is matched against a table of these programs, and a note only appears when both halves line up: that airline, at that hub, on a ticket you are actually being shown.
- TAP Air Portugal, Lisbon or Porto
- Up to 10 nights, no extra airfare
- Icelandair, Reykjavík
- Up to 7 nights on transatlantic itineraries
- Turkish Airlines, Istanbul
- Free hotel night(s) on qualifying connections; free city tours on 6–24h layovers
- Iberia, Madrid
- Up to 6 nights, no fare change
- Also in the table
- Emirates, Qatar, Singapore, Finnair, Ethiopian, Copa, Air Canada, Etihad
This is the difference between nine hours in a city and four days in it, on the same ticket — the one hack here where the airline is on your side.
The catch. They have to be booked with the ticket, usually direct with the airline; buying through a third party often forfeits them, and terms change constantly, so every note links to the airline's own page.
- Short connections are not free cities, and how short is short depends on the airport: five hours is enough at Schiphol and not at Istanbul, which wants eight. The card compares your gap against that airport's own figure, and against the careful default when it is an airport nobody here has assessed — it will not invent a number for one.
- An overnight connection is a city you cannot use unless you pay for a bed or stay up. It is flagged “overnight” instead of counted as a free day, and what the gap is worth is worked out from when it falls: only the daylight hours count, and only what is left after the airport takes about ninety minutes at each end.
- You have to be allowed into the country. A US passport needs a UK ETA to leave Heathrow and a Türkiye e-visa to leave Istanbul; the plan attaches the official link for every layover country on your route.
- A long connection usually means a longer, more tiring journey, and one delay can eat the whole visit.
- Immigration, a bag re-check on some itineraries and the ride into town take real hours. Budget the airport's minimum, not the raw layover length.
This is one ticket. If the first flight is late the airline rebooks you, your bags are checked through, and the only thing you can lose is the visit.