Largest airlines in the world rankings can look very different depending on whether you measure fleet size, passengers carried, or capacity (ASMs/ASKs). In this guide, we rank the Top 7 by fleet size for 2025, then show how the leaderboard changes when you switch to passengers and capacity. We also include quick profiles for each airline, network insights, and the reasons these rankings move year to year.
Method note: Fleet size is the cleanest, most consistently reported snapshot across airlines. Counts change monthly as aircraft are delivered, retired, or returned from storage, so treat the numbers below as a September–October 2025 snapshot.
Methodology: What “Largest” Really Means
“Largest” can mean several things in aviation. Here’s how each metric works and why results differ:
- Fleet size (our main metric): the number of aircraft in the airline’s mainline fleet. This is the simplest apples-to-apples count and the most common way general audiences interpret “largest airline.”
- Capacity (ASMs/ASKs) & seats scheduled: ASMs (Available Seat Miles) or ASKs (Available Seat Kilometres) measure how much capacity an airline offers, not just how many aircraft it has. Airlines with long-haul networks (e.g., Gulf carriers) can rank very high here even with smaller fleets.
- Passengers carried: total travelers transported in a period. High-frequency, short-haul airlines can rank strongly on passengers even if their ASMs are lower than long-haul peers.
Primary sources for these views include the Wikipedia “Largest airlines in the world” index (for consolidated lists), OAG schedule analysis (for seat capacity), IATA traffic updates (for RPK/ASK demand), and U.S. DOT/BTS for American traffic trends. We also check airline investor/fleet pages for up-to-date fleet totals.
The Top 7 Largest Airlines in the World (2025) — by Fleet Size
At a glance: The worldwide top three by fleet size in 2025 are United Airlines, American Airlines, and Delta Air Lines. China’s “big three” remain near the top 10, while Southwest Airlines and Ryanair Group continue to place highly thanks to single-aisle scale and utilization.
#1 United Airlines — global leader by fleet (≈1,000+ aircraft)
United sits at or near the top by fleet size in 2025, reflecting sustained narrow-body orders, a deep wide-body lineup for long-haul, and an expansive U.S. and international network. United also led ASMs in 2024, underscoring how its long-haul strengths convert fleet into capacity.
- Hubs & reach: Major U.S. hubs (EWR, IAH, ORD, DEN, SFO, LAX) feeding North America, trans-Atlantic, and trans-Pacific.
- Why it ranks: Balanced narrow-/wide-body strategy; heavy long-haul flying; strong aircraft order book.
- Good to know: A big fleet doesn’t just boost capacity—it provides flexibility to shift aircraft where demand is hottest.
#2 American Airlines — near four figures in fleet
American’s fleet remains close to the four-digit mark, keeping it in the global top three by size. By seats scheduled in 2024 (per OAG), American ranked #1 globally, a reminder that “largest” can look different by metric.
- Hubs & reach: Focused U.S. hubs (DFW, CLT, MIA, PHX, PHL, DCA, ORD, LAX).
- Why it ranks: Tremendous domestic depth, high frequencies, and strong North American connectivity.
- Good to know: American’s leadership in seats scheduled illustrates how dense short-/medium-haul networks win on volume.
#3 Delta Air Lines — scale with operational reputation
Delta’s fleet sits just shy of the top two by raw count, pairing a broad domestic network with premium long-haul service. Its MRO arm (TechOps) and reliability scores are often cited as pillars of operational consistency.
- Hubs & reach: ATL, DTW, MSP, SLC, LAX, SEA, BOS, JFK.
- Why it ranks: Robust wide-body fleet for long-haul; deep domestic frequencies; balanced network strategy.
- Good to know: Delta’s brand strength and on-time performance help it extract outsized value from fleet capacity.
#4 China Southern Airlines — Asia’s largest by fleet
China Southern remains a powerhouse with a large narrow-body base and a growing long-haul footprint. Domestic traffic recovery and regional growth contribute to its high fleet position.
- Hubs & reach: Guangzhou (CAN) and other Chinese hubs across a dense domestic network.
- Why it ranks: Mainland China demand scale; steady deliveries of A320neo/737 families.
- Good to know: Domestic networks in huge geographies (U.S., China) boost fleet counts due to frequency demand.
#5 Southwest Airlines — the largest all-737 operator
Southwest typically ranks top-five by fleet despite focusing mainly on the U.S. and neighboring international markets. Its single-type strategy (Boeing 737 family) drives crew scheduling efficiencies and tight turn times.
- Hubs & reach: Point-to-point emphasis with big operations in DAL, HOU, DEN, MDW, PHX, LAS, BWI, among others.
- Why it ranks: Massive single-aisle scale + high utilization.
- Good to know: Short-haul specialists can rival network carriers on fleet size because frequency requires more aircraft.
#6 China Eastern Airlines — another Chinese giant in the top tier
China Eastern maintains a very large narrow-body fleet anchored around its Shanghai hubs, with long-haul growth calibrated to demand and delivery schedules.
- Hubs & reach: PVG and SHA with extensive domestic coverage and selective long-haul.
- Why it ranks: Dense domestic core; consistent narrow-body deliveries.
- Good to know: As long-haul rebounds, capacity (ASMs) can rise faster than fleet if stage lengths extend.
#7 Ryanair Group — Europe’s ULCC scale champion
Ryanair Group’s scale and utilization keep it among the world’s fleet leaders even with shorter stage lengths. The group continues to induct 737-8-200s and looks ahead to next-gen deliveries.
- Hubs & reach: Pan-European model with strong presence in Ireland, UK, Spain, Italy, Poland, and more.
- Why it ranks: Ultra-low-cost model thrives on fleet scale, fast turns, and high seat density.
- Good to know: On passengers carried and load-driven metrics, Ryanair often punches above its fleet rank.
Close contenders: Air China and Turkish Airlines frequently appear in top-10 lists and can trade spots with #6–#8 depending on the snapshot date and whether you look at fleet, seats, or capacity.
Largest by Capacity and Passengers: How the Leaderboard Shifts
Switch the lens from fleet size to capacity and passengers, and the picture changes:
- By ASMs (capacity): Long-haul carriers gain ground because long sectors multiply seat-miles quickly. In 2024, United led ASMs, with American and Delta also near the top. Long-haul specialists such as Emirates and Qatar Airways rank higher here than by fleet size.
- By seats scheduled: According to OAG’s 2024 data, American scheduled the most seats globally, followed by other U.S. majors and large short-haul carriers like Ryanair and Southwest.
- By passengers: Carriers that dominate short-/medium-haul, high-frequency markets often lead passenger tallies. In the U.S., DOT/BTS data shows post-pandemic records through late 2024–2025, benefiting airlines with dense domestic schedules.
Why this matters: If you need the “biggest” airline to maximize available capacity (ASMs) for long-haul cargo/belly space or premium long-haul inventory, your ranking differs from someone seeking short-haul frequency or lowest fares.
Network Size & Global Reach
Fleet size is only one dimension of “largest.” Network design in terms of how many destinations and countries an airline serves shapes the customer experience and market coverage.
- Most countries served: Turkish Airlines often leads this metric thanks to Istanbul’s geographic position bridging Europe, Asia, Africa, and the Middle East. A carrier can rank lower on fleet size and still be #1 by countries served because of network strategy.
- Most destinations: U.S. majors (e.g., United) and pan-European ULCCs (e.g., Ryanair) appear near the top due to breadth across domestic/regional points.
For travelers and corporate travel managers, these network stats can be more useful than raw fleet size—more countries served can translate to better connectivity and single-ticket itineraries.
Why Rankings Change: Orders, Retirements, and Supply Chains
Three forces move these tables more than anything else:
- Order books & deliveries
Bulk orders of narrow-bodies (A320neo/737 MAX families) drive steady fleet growth. Wide-body deliveries (A350, 787) shift ASMs faster than raw fleet because of longer stage lengths and more seats per aircraft. - Retirements & cabin densification
Retiring older jets can reduce fleet counts but raise capacity if replacements have more seats or higher utilization. Cabin densification and premium-economy installations can also change capacity without changing fleet numbers. - Production & supply chain constraints
Engine availability, MRO turnaround times, and OEM production rates (Airbus/Boeing) can delay deliveries and push expected rank moves into next year. As supply chains loosen, expect faster movement among the #4–#12 spots.
Quick Airline Profiles (Top 7 Recap)
- United Airlines: U.S. network + long-haul depth; high ASMs; diversified fleet.
- American Airlines: Seat capacity leader in schedules; massive U.S. coverage; strong Latin America.
- Delta Air Lines: Operational reputation; premium lean; broad partner network.
- China Southern: Asia’s largest by fleet; strong domestic base.
- Southwest: World’s largest all-737 operator; frequency-driven network.
- China Eastern: Large Shanghai-centric footprint; rebuilding long-haul selectively.
- Ryanair Group: Europe’s ULCC scale; high utilization; consistent growth pipeline.
FAQs
What is the largest airline in the world in 2025?
By fleet size, United Airlines edges out competitors at the time of writing. By ASMs (capacity) in 2024, United also led. By seats scheduled in 2024, American Airlines ranked #1.
Is “largest” the same as “best”?
No. “Largest” is a structural metric (fleets, capacity, passengers). “Best” depends on what you value: on-time performance, cabin experience, loyalty benefits, network fit, or fares.
Why do Gulf carriers rank high on ASMs?
Long-haul, intercontinental routing via mega-hubs (e.g., Dubai, Doha) yields very high seat-miles per aircraft, which lifts ASMs even with fewer aircraft than U.S./Chinese giants.
Which airline serves the most countries?
Turkish Airlines commonly holds this title, leveraging Istanbul’s geography to reach more countries than any other carrier.
How often do these rankings change?
Monthly, in small ways (deliveries/retirements). Bigger shifts happen when large order books start arriving in volume or when regulatory/market changes reshape networks.
I’m an aeronautical engineer (B1.1 License), a fan of travel, technology, and entrepreneurship. I’m also interested in writing and programming.