Global hubs expand again, but demand will decide the winners

Global airport seat capacity has become an increasingly important reference point for understanding how the aviation industry is evolving, particularly in periods of uneven demand and structural change.

Unlike passenger statistics, capacity reflects forward-looking decisions by airlines and airports, shaped by expectations around growth, competition, infrastructure limits and operating economics.

The world's largest airports continue to be dominated by a relatively small group of mega hubs, yet the similarities largely end there.

Differences in domestic versus international reliance, hub-and-spoke intensity, airline concentration and low-cost penetration result in widely varied outcomes from superficially comparable levels of capacity.

Infrastructure design also plays a decisive role, with runway availability, operating hours and aircraft mix often proving more influential than terminal size alone.

Recent years have underscored how capacity can expand or contract independently of underlying demand, influenced by fleet availability, regulatory constraints and geopolitical factors. As a result, headline capacity rankings provide only partial insight into performance or resilience.

Understanding how and where capacity is being deployed therefore offers a useful framework for assessing strategic intent across the industry.

However, it also highlights the limits of capacity as a standalone metric, reinforcing the need to interpret it alongside utilisation, yield and long-term sustainability when assessing the true health of global aviation.

OAG's annual review of seat capacity by airport, in this case for 2025, reveals the usual suspects heading the Top 10 list - the 'Mega hubs', that handle a hefty percentage of the world's air travellers, and especially those in transit. This report is based on the original OAG report together with CAPA - Centre for Aviation's observations on it.