OAG Aviation Worldwide Limited, a UK-based analytics company that has been collecting airport statistics since 1929, has released its annual Megahub Index. This is a data-driven study of which airports around the world are best at getting travelers from point A to point B (and C, D).
2025 report name The most convenient airport is London Heathrow Airport on earth Chicago O’Hare International Airport tops list of U.S. airports.
This “connectivity” ranking is based on the number of flights each airport can connect to within a six-hour period on the busiest day of the year. This is a metric that speaks not only to an airport’s size, but also to its efficiency, schedule, and influence on global air travel.
What else do rankings measure?
OAG’s rankings don’t just count the number of lines an airport has, they measure how well those lines are linked. Specifically, the index calculates the number of flights a passenger can connect to within a six-hour window on a single peak travel day. This means that a small airport with a very well-timed network, for example one where many flights arrive and depart in coordinated waves, may be able to score higher than a busy airport with a spread out flight schedule.
That is one of the reasons why Istanbul Airport has performed so well this year. Turkish Airlines has built its schedule around tightly synchronized connections that make connections seamless. Los Angeles International Airport serves more destinations overall, but flights are not lined up as well. This report looks at how airports function as transfer machines. (Of course, there are other great options for transit hubs, such as airports with great stopover programs.)
These are the most connected airports in the world, and you can see why connectivity is important.
The most connected airport in the world
London Heathrow Airport has achieved the world’s top spot for the third year in a row, thanks to its dense route network and role as a transatlantic gateway connecting Europe, North America and the rest of the world. On its busiest day, Heathrow Airport offered more than 59,000 potential connections to 226 destinations.
“Heathrow’s continued dominance reflects its important role in global travel, while Istanbul’s rapid rise shows how hubs are evolving to meet demand,” OAG principal analyst John Grant said in the report.
Turkey’s Istanbul Airport (IST) jumped from eighth place in 2024 to second place this year, reflecting its rise as a major global hub for Europe, Asia and the Middle East. Amsterdam Airport Schiphol ranked third, up from fourth place in 2024. Chicago, the highest ranked U.S. airport, ranked seventh, up from ninth last year.
The top 10 most connected airports in the world are:
- London Heathrow Airport (LHR)
- Istanbul Airport (IST)
- Amsterdam Schiphol Airport (AMS)
- Kuala Lumpur International Airport (KUL)
- Frankfurt International Airport (FRA) (tied for 4th place)
- Seoul Incheon International Airport (ICN)
- Chicago O’Hare International Airport (ORD)
- Atlanta Hartsfield Jackson International Airport (ATL)
- Tokyo Haneda Airport (HND)
- Paris Charles de Gaulle Airport (CDG)
Most connected airport in the US
Domestically, Chicago O’Hare International Airport regained the title as the busiest airport in the United States, narrowly beating out Atlanta’s Hartsfield-Jackson International Airport (ATL), which shared the top spot in 2024. At its peak in 2025, O’Hare International Airport offered the largest combination of flights possible, offering 214 domestic destinations and more than 76,000 connecting flights.
The top 10 most accessible airports in the United States are:
- Chicago O’Hare International Airport (ORD)
- Atlanta Hartsfield Jackson International Airport (ATL)
- Dallas Fort Worth International Airport (DFW)
- Denver International Airport (DEN)
- Charlotte Douglas International Airport (CLT)
- Seattle-Tacoma International Airport (SEA)
- Boston Logan International Airport (BOS)
- Detroit Metropolitan Wayne County Airport (DTW)
- Houston George Bush Intercontinental Airport (IAH)
- Los Angeles International Airport (LAX)
.
Why connectivity matters to travelers
For travelers, airport connectivity can have an incredible impact on the experience of getting from one destination to another.
Essentially, a well-connected airport means less hassle and more flexibility when traveling. Connectivity hubs make it easier for airlines to synchronize schedules, reduce connection times, smooth connections, and reduce the risk of missed connections. If a flight is canceled or delayed, airports like Heathrow and O’Hare typically have multiple backup options to get passengers on board within hours rather than days.
Connectivity also correlates with more competitive fares. When multiple airlines operate similar routes through the same hub, they tend to lower prices and offer a wider range of departure times.
