Last year, London Heathrow was crowned the most connected airport in the world. The west London hub offered travellers flights to an impressive 226 destinations across 80 different countries and so, as you’d expect, it got very, very busy. In fact, a new report revealed that Heathrow was the world’s second-busiest international airport in 2025.
OAG looked at flight schedules data from January to December 2025 to discover which airports were the busiest internationally and globally (the latter included domestic flights) across Europe. The report reckoned that LHR had 49 million scheduled international seats in 2025, which is one percent more than in 2024 and four percent more than in 2019.
When OAG added together its international and domestic seat capacity, Heathrow emerged as Europe’s busiest airport and the fourth busiest in the world. Altogether, it had 52.1 million scheduled seats in 2025. Globally, the London airport was beaten by Tokyo Haneda Airport, Dubai International Airport and Atlanta Hartsfield-Jackson International Airport, which took the top spot.
The accolade comes a few days after Heathrow announced that it handled a record number of passengers in 2025 – 84.5 million. That’s an average of more than over 231,000 people arriving and departing each day. It also had its busiest ever December, with 7.2m passengers in total.
Photograph: Shutterstock
Obviously, there’s a major gap between OAG’s seat capacity data and the actual number of passengers passing through Heathrow. Scheduled seat capacity is often a lot less than actual seats taken up because airlines tend to reduce their planned capacity during uncertain periods. It also isn’t clear where OAG’s schedules analyser counts connecting flights.
As its passengers number rise, Heathrow is waiting on approval for an enormous £49 billion expansion. The ‘once-in-a-generation redesign’ includes a third runway, a new terminal and a new junction on the M25, and hopes to boost annual capacity to a whopping 150 million.
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