OAG Aviation Worldwide Limited, a U.K.-based analytics company that’s been collecting airport statistics since 1929, has released its annual Megahubs Index—a data-driven look at which airports around the world are best at getting travelers from Point A to Point B (and C, and D).
The 2025 report names London Heathrow as the most connected airport on the planet, while Chicago O’Hare International Airport tops the list of U.S. airports.
That “connectivity” ranking is based on the number of possible flight connections within a six-hour window on each airport’s busiest day of the year. It’s a metric that speaks not just to the size of an airport, but also to its efficiency, scheduling, and influence in global air travel.
What else the ranking measures
OAG’s ranking doesn’t just count how many routes an airport has—it measures how well those routes link together. Specifically, the index calculates how many possible flight connections passengers could make within a six-hour window on a single, peak travel day. That means a smaller airport with an extremely well-timed network—say, one where many flights arrive and depart in coordinated waves—can score higher than a busier airport where flight schedules are more spread out.
That’s in part why Istanbul Airport scored so well this year—Turkish Airlines has built its schedule around tightly synchronized connections that make transfers seamless. Los Angeles International Airport serves more destinations overall, but its flights don’t align as neatly. The report looks at how airports work as a transfer machine. (Of course, there are others ways to excel as a transfer hub, including airports that offer incredible stopover programs.)
These are the world’s most connected airports—and why that connectivity matters.
The most connected airports in the world
London Heathrow claimed the top spot globally for the third year in a row, thanks to its dense network of routes and its role as a transatlantic gateway linking Europe, North America, and beyond. On its busiest day, Heathrow offered more than 59,000 potential connections to 226 destinations.
“Heathrow’s sustained dominance reflects its vital role in global travel, while Istanbul’s rapid rise shows how hubs are evolving to meet demand,” John Grant, OAG’s chief analyst, stated in the report.
Turkey’s Istanbul Airport (IST) jumped from eighth place in 2024 to second this year, reflecting its emergence as a major global hub among Europe, Asia, and the Middle East. Amsterdam Schiphol ranked third, up from fourth in 2024. Chicago, the highest ranking U.S. airport, ranked seventh, up from ninth last year.
These are the 10 best connected airports in the world:
- London Heathrow (LHR)
- Istanbul Airport (IST)
- Amsterdam Schiphol Airport (AMS)
- Kuala Lumpur International Airport (KUL)
- Frankfurt International Airport (FRA) (tied for 4th)
- 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)
Midwestern megahub Chicago O’Hare offers the most robust roster of connecting flights of any airports stateside.
Courtesy of Erol Ahmed/Unsplash
The most connected airports in the United States
Domestically, Chicago O’Hare International reclaimed the title of most connected airport in the United States, narrowly edging out Atlanta’s Hartsfield-Jackson International (ATL), which it shared the top spot with in 2024. On its peak day in 2025, O’Hare offered the most possible flight combinations and served 214 domestic destinations and more than 76,000 possible connections.
These are the 10 best connected airports in the United States:
- 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)
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Why connectivity matters for travelers
For travelers, airport connectivity can have a surprisingly big impact on the experience of getting from one destination to another.
At its core, a well-connected airport translates to fewer travel headaches and more flexibility. High-connectivity hubs make it easier for airlines to synchronize their schedules, which means shorter layovers, smoother transfers, and a reduced risk of missed connections. If a flight gets canceled or delayed, airports like Heathrow or O’Hare typically have multiple backup options to get passengers on their way within hours rather than days.
Connectivity also correlates with more competitive fares. When several airlines operate similar routes through the same hub, it tends to drive prices down and open up a greater range of departure times.
