How much connection time do I need between flights?

At a glance#

What minimum connecting time actually says#

Between two itineraries at the same price to the same destination, the connection time decides how the travel day goes. It appears as a single number in a search, and it says less than most travellers assume.

Every airport publishes a minimum connecting time, and booking systems sell nothing below it, which creates the impression that anything offered is safe. The figure describes the shortest path under ideal conditions: an on-time arrival, a nearby gate and no additional screening.

So the minimum is a floor. Whatever buffer an itinerary has lies in the time booked beyond it. Minimum connecting time answers whether an itinerary may be sold, not whether it will work, and those are two different questions.

The clock runs from the scheduled arrival, not from the moment the door opens, and at large airports those two moments sit ten to twenty minutes apart. The number also describes the airport’s infrastructure and says nothing about how punctual the airlines are. Two airports with the same minimum time can behave very differently on an ordinary Tuesday.

Responsibility is the part travellers tend to miss. Booking an itinerary the system offers means a full claim to rebooking if the connection fails, as missing a connection describes. The minimum time protects that claim; it does not protect the trip.

The factors that cost time#

The walk inside the terminal#

Three quantities determine how much time a connection needs: the walk inside the terminal, a possible repeat screening and the time of day. None of them sits in the minimum connecting time, and all three can be looked up before booking.

A connection within one terminal is the simplest case. The distances are short and the time usually holds even with a mild delay. A terminal change costs considerably more, because waiting for a transfer bus or train comes on top, and those do not run every minute.

Terminal changes vary a lot in price. A change on an internal train inside security costs ten minutes; a change by bus outside security costs half an hour plus the screening afterwards. The airport’s own pages settle the question in two minutes.

At large hubs the walk itself is the largest item, and twenty minutes on foot is normal there. At sprawling airports another quarter of an hour can sit between screening and the furthest gate, while boarding closes well before departure.

Screening and immigration#

Disembarking eats into the time before anyone starts walking. On a full long-haul flight twenty minutes can pass between arrival at the stand and the last passenger reaching the door, and anyone seated at the back loses all of it.

A repeat security screening is the second large item. It applies when the transfer leaves the secure area or crosses between areas with different standards. The queue there varies strongly by hour: early morning and early evening are the longest, because that is when the departure waves leave.

Immigration is the most expensive item of all. It is mandatory at some destinations, it brings baggage reclaim with it, and it happens more often than most expect. Some countries require entry even where the bag would otherwise be through-checked, and the connection time needed then doubles compared with a pure transit.

Time of day and season#

The time of day acts on all of these at once. At peak hours the walkways are fuller, the queues longer and the transfer buses more crowded, and the difference from a quiet hour is easily twenty minutes. The season matters too. During school holidays and around public holidays screening times lengthen noticeably, and a connection that works in November is tight in August.

The first wave of the morning is the most punctual, because the aircraft stood overnight at the airport. Delays accumulate with every later wave, so a tight connection early in the morning is more reliable than the same connection in the evening.

Worked example: one airport, several itineraries#

Take several itineraries through the same airport that differ only in connection time and terminal.

Itinerary A is the baseline. Within one terminal the walk is short, and as long as the inbound lands on time the connection holds, even with a few minutes lost at the stand. A delay of half an hour is a different matter, and there is nothing in reserve to absorb it.

Itinerary B is the most common trap. It satisfies the minimum connecting time and is still a poor choice, because the terminal change alone uses up what little margin there is.

An hour above the minimum, as in C, works best for most trips. It absorbs the usual small delays and lengthens the journey by a manageable amount. Doubling that to two hours, as in D, does not make the itinerary twice as safe; the gain in safety flattens out while the waiting grows.

Immigration with reclaim, screening and recheck consumes more time than travellers expect, and none of it can be hurried. That is why E, with the same nominal margin as A, sits at the bottom of the assessment.

F shows how little the column means on its own. Three hours on separate tickets are worth less than one hour on a single booking, because in one case the traveller carries the risk and in the other the airline does.

What changes on separate tickets#

On a single booking the system checks the minimum connecting time, and a missed connection is rebooked at no cost. On separate tickets nobody checks anything. An impossible connection can be bought, and on screen it looks the same as a workable one.

Baggage comes on top. On separate tickets it is not through-checked and has to be reclaimed and checked in again, as through-checked baggage describes. The measure is then the time for reclaim, the walk, a new check-in and screening, as separate tickets sets out, and the published minimum stops mattering.

Three hours is the floor on separate tickets, with no buffer included. Planning less buys a risk the traveller carries, for a saving that sits below the price of the second ticket.

Booking such an itinerary anyway means planning it as two trips: packing so the bag is carryable at the transfer, booking the second flight refundable, and never placing it on the last departure of the day.

When it is not worth adding more buffer#

Extra time stops lowering the risk in several situations:

• When the inbound is the last one of the day. Only an earlier flight helps, not a buffer.
• On a delay of several hours. It exceeds any sensible margin.
• When the onward flight operates once a day. Rebooking is the answer, and time cannot replace it.
• Beyond roughly three hours of buffer. Only the layover grows.
• At very small airports. The walks are short and the queues empty, so a buffer buys less safety there than elsewhere.

At airports with known screening bottlenecks the picture runs the other way. Extra time helps there, and the addition is the best investment in the whole booking. Travelling with children or with a lot of hand luggage pushes in the same direction: the walks take longer, and the addition to the minimum time rises accordingly.

Seat choice is a smaller lever. Sitting near the front on a tight connection recovers the time disembarking otherwise costs, and it is the only lever still available on the day itself, as seat selection fees describes.

Whether both flights are operated by the same airline or by partners is worth checking as well. With partners the handover of bags and booking data is routine; between airlines without an agreement it is not, as codeshare describes.

What makes a booking better#

A handful of decisions lower the risk more than any additional half hour.

Booking the trip as one itinerary moves the risk to the airline. Connecting within the same terminal removes the largest single item. Taking the earlier departure of the day leaves a later one in reserve, and carrying what is needed for the first hours defuses any rebooking.

The hour of the connection matters as much. A connection late in the morning meets empty queues and one at seven in the morning meets full ones, and that difference exceeds half an hour of extra buffer. So does the connecting airport itself: a smaller hub with short walks is the more reliable option at the same connection time, and that choice is made at booking and never again.

Airports with separate areas for different airlines are a special case. A connection between two partners can be shorter there than one within a single airline, because the gates sit closer together. The infrastructure sets the rule, whatever logo is on the aircraft.

Portals display all this unevenly. Some show the connection time in hours and minutes, others only the total journey time, and the critical number cannot be read off a total. Comparing two offers means working it out from the individual flight times.

Adding terminal, screening and time of day to the calculation shows the difference between two itineraries that look identical on screen. Buffer helps up to a limit; the form of the booking helps every time.

Put together, the conditions are short: one booking, same terminal, no immigration, a quiet hour, and then an hour above the minimum is enough. Missing one of those raises the buffer needed, and missing two makes a different itinerary the better choice.

The most common mistakes#

• Treating the minimum as a buffer. It is a floor, and the buffer only starts above it.
• Counting from the door opening. The clock runs from the scheduled arrival at the stand.
• Overlooking a terminal change. At a large hub it is the largest single item in the connection.
• Planning separate tickets tightly. Reclaim, check-in and screening all have to fit, along with the walk.
• Choosing the last departure of the day. An earlier flight leaves a reserve behind it.
• Travelling without a day of essentials in the cabin. A rebooking hurts far less with them in the hand luggage.

Related topics#

• Missing a connection
• Separate tickets
• Through-checked baggage
• Codeshare
• Reading fare rules
• When to book