The Boeing 777-9 is soon to be the largest commercial aircraft on the market. When the 777 family was first developed in the 1990s, it wasn’t intended to be the largest passenger airplane, or even the largest airplane. Boeing updated its 747 to the 747-8I, but while the freighter variant proved somewhat popular, the passenger variant did not.

With the cancellation of the 747 in 2023 and the Airbus A380 in 2021, the 777 was, by default, the largest airplane on the market. The aircraft is the widest single-aircraft in existence, and its internal cabin width is wider than that of the A380 upper deck and much wider than that of the 747 upper deck. So, how do the cabin widths of the world’s largest single-deck, twin-engined airliner compare with those of the world’s largest double-decked, quad-engined aircraft?

Airbus A380 Cabin Widths

When comparing aircraft width, it is important to examine the differences between external width and internal width. The A380’s external fuselage is approximately 23 feet and five inches (7.1 meters) in diameter. With the new production standard for the A350 airliner, the walls have been made two inches thinner, allowing the internal cabin to be four inches wider.

The A380 has two decks. The main deck cabin width is 21 feet and four inches (6.5 meters) in usable width. The upper deck is smaller than the main deck, measuring 19 feet (5.8 meters) in usable width. While there are no published figures for the width of the deck’s ceiling versus floor, the sidewall curvatures indicate the upper deck’s ceiling is slightly narrower.

As the A380 is a large double-decked aircraft, it is built with significant floor beams and supports between decks. Its walls and frames are robust. Airbus pioneered thinner cabin walls on the A380 by using advanced composites and insulation materials. The average wall thickness is 8-10 inches on each side.

Boeing 777 & 777X Cabin Widths

The 777 is now entering its third generation. Consequently, some of its physical dimensions have changed over time. The most noticeable change for the casual onlooker with the upcoming 777X is the longer wingspan and novel folding wingtips. Legacy -200 and -300 family jets have an internal cabin width of approximately 19 feet, three inches (5.87 meters).

Thanks to design improvements that allow Boeing to make the walls thinner, the upcoming 777X will have an additional four inches of usable internal cabin width. The thinner sidewalls and optimized insulation will increase the internal width to 19 feet, seven inches (5.97 meters). It should be noted that the 777X does not compete with the terminated A380; it competes with the A350, which is why Boeing says that it will be « up to 40 cm (16 in) wider than the A350. »

Both the legacy 777s and upcoming 777X will have wider internal cabins than the A380’s upper deck by three inches and seven inches, respectively. The A380’s upper deck is one foot and nine inches wider than the 777X. This translates to much more comfortable 10-abreast seating. For reference, the A350 originally had an internal cabin width of 18 feet and five inches (5.61 meters), which has since been extended to 18 feet and nine inches (5.71 meters).

Boeing 777X Vs. A380 Cabin Length

Just because the A380 is a bigger and wider airplane doesn’t mean it’s longer. The cabin lengths on legacy 777-200s/-300s were around 143 feet (43.6 meters). This rises to around 180 feet (54.9 meters) for the larger 777-300ER, the most popular 777 variant. The upcoming 777-8 variant will replace the smaller -200 variants and will have a cabin length of around 159 feet (48.4 meters). This means the 777-8 will be around 16 feet longer than its predecessor.

Something is similar when it comes to the more popular stretched 777-9 variant that will replace the 777-300ER. It will have a cabin length of around 189 feet and six inches, or around nine feet longer than the 777-300ER. This will enable it to comfortably carry 34 more passengers than the -300ER. This is a little misleading as due to regulations from its redesigned exit doors, the 777-9 will have a theoretical maximum capacity of just 475 passengers, down from the -300ER’s 550-seat limit.

The A380 has a main deck length of around 164 feet (50 meters) and an upper deck length of around 147 feet (44.8 meters). It may be a much larger airplane with two complete decks, but each of those decks is shorter than the single 777-300ER and 777-9 deck, but longer than the 777-200 deck. The 777-8’s deck will be sized between the A380’s decks, while the 777-9’s deck will be around 25 feet longer than the A380’s main deck and 42 feet longer than the upper deck.

Nine Vs. 10 Abreast Seating

The A380, A350, and 777 and 777X are all wide enough to accommodate ten-abreast seating in economy class. But while 10 economy class seats can be squeezed into all these aircraft, the internal cabin widths result in varying levels of comfort. As an extra-wide aircraft, no A380 has been configured with nine-abreast economy class seating (3-3-3); all have 3-4-3. Especially on the main deck, the aircraft has plenty of room for a 3-4-3 configuration.

The picture starts to change with the narrower 777. In the early days of the 777, most operators used a nine-abreast (3-3-3) configuration in economy. At the time, the industry standard had relatively wide seats of around 18.5 inches. However, over time, most airlines switched to ten-abreast seating (3-4-3). The extra four inches in the 777X will make the 10-abreast seating more comfortable.

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The A350 can technically fit 10 seats abreast, but because it is narrower than the 777, this is uncomfortable. Almost all airlines have elected to configure them 3-3-3 in economy. Only ​​​​​​​Air Caraïbes, Philippine Airlines, and French Bee have configured these aircraft 10-abreast, resulting in high-density A350s. It’s unclear how many more airlines will configure 10 abreast now that the new A350s have another four inches to play with.

Wingspans & ICAO Regulations

Talk of aircraft widths is mostly concerned with the fuselage and the internal cabin width. But another interesting dimension of width is the wingspan. The legacy Boeing 777s and the A350s have relatively straightforward wingspans, as they were designed to fit within ICAO Code E regulations.

However, the massive A380 has wingspans of 261 feet and eight inches (79.75 meters). This made it Code F, requiring airports to install special infrastructure to operate the jet. One notable feature of its wings is that the wingtip devices are wingtip fences, which are typically found on narrowbody A320s instead of the blended or raked winglets of widebodies. This was partly to limit the wingspan.

The 777X is coming with a Code E workaround by incorporating folding wingtips. Overall, the 777X is claimed to be 5% more aerodynamic than the A350, partly thanks to its extended wings (235 feet and seven inches or 71.8 meters). Time will tell whether this was a wise move by Boeing; the added complications and novel design may be contributing to the program’s delays.

The A380’s Main Deck Is The Widest Ever

In terms of economy class configurations, the differences in cabin width between the 777 family and the A380 are not significant. This is because the airline industry has already accepted having thinner economy seats, allowing the 777 to be configured ten abreast, just like the A380. The extra four inches in cabin space will make this more comfortable, and much more comfortable than a squishy ten-abreast A350.

It’s also worth noting that theoretical maximum density configurations are rarely relevant. The ​​​​​​ 777-300ER could theoretically carry 550 people, but in practice, these aircraft are operated by mainline carriers for long-haul flights and are not configured with nearly that many seats. Acknowledging that, Boeing has increased the number of passengers the 777-9 can comfortably carry by 34, while slashing its legal limit to just 475 seats (the A350-1000 is certified for 480).

Overall, the Airbus A380 is the widest cabin ever built. With a main deck internal width of 21 feet, four inches (6.5 meters), it is wider than the 747’s main deck of 20 feet (6.1 meters), and much wider than the 777X and A350. That said, the 777X is wider than the A380’s upper deck, although the upper deck is still wider than the A350. Separately, the upper deck of the 747 was noticeably narrower at just 16 feet and one inch (4.9 meters).