How the planner finds it
- For every flight leg, hub candidates are ranked by detour — how much further A → hub → B is than A → B. A hub only qualifies if the detour is under 1,500 km or 60% of the direct distance, and cities already on your route are skipped, because a day somewhere you are staying anyway is not a bonus.
- Phase one prices those candidates from cached fares, no times needed, and keeps the ones that are not wildly above the through fare. At most one candidate per leg goes through in the first pass, so several legs get a look instead of one leg taking every slot.
- Phase two prices the survivors properly. Kiwi is searched first because it is free, across three times as many candidates; only the best few then get a paid Google search for real times.
- The gap between the two tickets is measured from the real arrival to the real departure. Under three hours inside Europe, or four hours anywhere else, is rejected outright — as is anything over 36 hours. When the two tickets are at different airports in the same city, three hours are added to that floor, because collecting a bag, crossing the city and checking in again as a new passenger is not something three hours buys.
- What the gap is worth is worked out from when it falls, not from whether it crosses midnight: the airport takes about ninety minutes at each end, and only the hours between 09:00 and 20:00 count as time in the city. A three-hour gap that happens to cross midnight is described as a night in the terminal, because that is what it is.
- Risk comes out of that gap: an airport change is high, an overnight gap is medium above eight hours and high below it, otherwise low above four hours (five internationally) and medium under that.
- A combo is kept even when it costs up to $40 more than the through fare, because a day in Budapest for $10 is a good trade and it should be your call, not ours.
- Kiwi's own multi-airline combos are a different animal and are labelled separately: sold as one booking with the Kiwi.com Guarantee, so a missed connection is rebooked by Kiwi. Those have to beat a through ticket by $40 per person before the planner recommends one.
Worked example
Milan → Budapest → Athens on two tickets
example output- Two tickets
- $70 per person
- Nonstop through fare
- $60 per person
- Difference
- +$10 per person
- What the $10 buys
- 22 hours in Budapest
- Risk
- Medium — overnight gap, not protected
Ten dollars for a day in a city is the point, not the saving. This is the shape to look for on your own plan: not every trip has one, and the example plan we publish came back with none, which is what the empty section is for.
When it does not work
- Separate tickets are not protected. If the first flight is late, cancelled or diverted, the second airline owes you nothing and you buy a new ticket.
- Bags are not checked through. You collect them, clear customs, and check in again.
- An airport change inside the hub — Gatwick to Heathrow, Orly to Charles de Gaulle — turns a gap into a commute, and is marked high risk for exactly that reason.
- You must be admitted to the hub country to do this at all, and some airlines want onward proof at check-in.
- Only a handful of candidates are priced live per plan, and phase one leans on cached estimates. A hub with no cached fares may never get a live look.
- Same-day connections are only tried when the first flight lands by 14:00. Otherwise the second ticket is the next day, which is the pattern that gives you the free day anyway.
- Kiwi's guarantee is Kiwi's, not an airline's. It covers rebooking under its own terms; read them before treating it like a normal connection.
Risk
Medium risk
Every combo carries its own low / medium / high badge, computed from the actual gap. Leave a real cushion — a missed second ticket costs more than the combo ever saved.