When it comes to widebody aircraft, Boeing’s upcoming flagship, the 777X, has a significant advantage over Airbus’ widebody flagship, the A350. However, with narrowbody aircraft, the European planemaker has the advantage with its Airbus A320 family of narrowbody aircraft being significantly wider than the Boeing 737. Separately, the A320neo family also features significantly wider CFM International LEAP-1A engines compared with the MAX family’s smaller LEAP-1B engines.

Once the world leader, the Boeing 737 is now notably squishy for a six-abreast narrowbody airliner, but this is something Boeing can’t change without completely redesigning the aircraft. Here is what to know about the Airbus A320 and Boeing 737 compared with internal cabin widths and how they measure up to the emerging industry standard.

Width Of The Airbus A320 & Boeing 737

Externally, the A320 family has a fuselage cross-section of 13 feet (3.95 meters), and, internally, the cabin width measures 12 feet and two inches (3.7 meters). The A320 was first introduced in the 1980s, and it has been built in successive generations of A319s, A320s, and A321s (plus the first-generation shortened A318). The widths of all these aircraft are the same, with the main difference being the length of the aircraft. The width of the updated A320neo is the same as that of the older A320ceo family.

The Boeing 737 family was first introduced in the 1960s, and it has an external fuselage width of 12 feet and four inches, making it eight inches narrower than the A320. The aircraft’s internal cabin width is 11 feet and seven inches (3.54 meters), making the 737 around nine inches narrower than the A320 on the inside. Both aircraft seat six passengers across in economy class, but it means that A320 passengers enjoy more space.

Separately, the A320neo family is typically longer ranged than the Boeing MAX family. The A321XLRs have an advertised range of up to 4,700 nautical miles, although the regular A321neo manages around 4,000 nautical miles. Meanwhile, the 737 MAX family has a maximum range of 3,800 nautical miles for the uncertified MAX 7, although the MAX 8 is the longest-range variant currently in service, and it has a maximum range of 3,500 nautical miles. Real-life ranges vary by payload, mission, and other factors.

Mixed Picture With Wider A320 Seats

If passengers hope this will translate into wider seats in A320 aircraft on low-cost carriers, they will normally be mostly disappointed. Most of the space is absorbed by aisle width, sidewall curvature, and other things. The typical seat on an A320 with low-cost carriers is typically around 17.5 to 18 inches wide, around half an inch more than the 17 to 17.5 inches seen with Boeing 737 low-cost carrier economy seats. The armrests and seat shells on Airbus A320s are typically slightly thicker.

This at least means passengers are spaced a little more. These seats typically feature less aggressive seat tapering at the hips and shoulders, which translates to passengers feeling a little less claustrophobic, although the seats are not much wider. Additionally, Airbus uses flatter sidewalls and more sculpted panels. While this doesn’t increase seat width, it does improve shoulder and head clearance somewhat. This helps to keep the windows a bit further from the seats.

The sidewall curvature is one of the reasons why the A320 can feel wider and roomier than the Boeing 737. On LCCs, the biggest beneficiary is typically the aisle, which is around an inch wider at 19 to 20 inches wide on the A320, while it is 18 to 19 inches wide on the 737. Meanwhile, the seats are typically wider on full-service carriers, where the A320 seats are typically 18.0 to 18.5 inches wide. It is very difficult for mainline carriers to do this with narrower 737s.

A320 & 737 Vs Other Narrowbody Aircraft

The A320 and Boeing 737 are by far the most popular narrowbody aircraft on the market, but not the only ones. The A320 has just overtaken the 737 to be the most delivered aircraft of all time, and more A320 family aircraft are currently on order than all other narrowbody aircraft combined. Elsewhere in the narrowbody sector, the Embraer E-Jet and A220 are currently filling the larger regional jet market.

The E-Jet comes with a cabin width of nine feet (2.74 meters), making it easily the narrowest aircraft considered here. The Airbus A220 (formerly Bombardier CSeries) is much wider than the E-Jet with a cabin width of 10 feet and nine inches (3.28 meters), which places it in the middle between the E-Jet and the Boeing 737. The E-Jet sits four abreast, and the A220 sits five abreast.

The now-sanctioned Russian MC-21 was built to be a 737 MAX and A320neo competitor, and it has a cabin width of 13 feet and four inches (3.96 meters), making it much wider than the A320. This is more space for passengers, as it also sits six abreast. The Chinese COMAC C919 is 13 feet (3.96 meters) across, also making it wider than the A320. Finally, the older mid-sized Boeing 757 airliner is similar to the A320 with an internal width of 12 feet and four inches (3.76 meters).

No Change To Cabin Widths

The Boeing 737 has now been produced in four generations: the 737 Original, 737 Classic, 737 NG, and 737 MAX. The MAX is expected to be the final generation, with Boeing now in the early stages of developing a clean-sheet successor. Over this time, the fuselage diameter has not been fundamentally changed.

What has changed has been the interior trim and bins, with Sky Interior introducing cabin improvements. However, the sidewall thickness and cabin diameter have remained essentially the same. The story is mostly the same for the A320, although Airbus has managed to introduce thinner sidewall panels and more sculpted linings. Still, this did not really result in cabin width increases like the A350.

By contrast, Airbus has introduced a new production standard for new-build A350s. It was able to make the cabin walls two inches thinner on each side, allowing the cabin width to grow by four inches, with no change to the aircraft’s overall fuselage width. Boeing has done the same with its upcoming 777X. Indeed, compared with the older generation Boeing 777-300ER, the 777X will have an extra four inches in cabin diameter.

Why The MC-21 Is Much Wider Than 737

It’s hard not to notice just how much wider the MC-21 is than the Boeing 737. The reason for this is mostly because the MC-21 is a newly designed clean-sheet jet, while the Boeing 737 is a fundamentally old 1960s design. When the Boeing 737 was designed, the infrastructure at airports was still limited. It was designed as a low, short-field aircraft with short landing gear and a small fuselage. At the time, 17-inch-wide seats were normal.

Boeing decided to design the aircraft with the smallest fuselage that could credibly sit six passengers abreast. In the airline industry, updates to aircraft can change with wings, engines, avionics, and the fuselage length. However, they can’t change the fuselage width, and rebarreling an aircraft would essentially be the same as making an all-new aircraft.

Russia designed the MC-21 in the 2010s explicitly to outcompete the A320 and 737 on comfort and economics. To that end, it chose to produce an aircraft with a very wide fuselage for a six-abreast aircraft, which allows the jet to have 18–18.5 inch wide seats and a wide aisle. The use of lightweight composites also allows it to offset the weight penalty.

The Boeing 737 Is Narrow, But Still Sets The Standard

When the 737 was first introduced in the 1960s, the narrowbody airliner was revolutionary. It is now the longest-produced commercial aircraft family and is set to remain in production into the 2030s and possibly the 2040s. However, over time, the industry standard has changed. Airbus introduced the wider A320 in the 1980s, and Russia and China built the extra wide MC-21 and C919 in the 2010s. The A220 is also wider in relative per-seat terms, adjusting for its five-abreast seating.

Still, the impact of the C919 remains limited as the aircraft is in a low rate of production, and the aircraft is unlikely to get certified in the United States and may also struggle elsewhere for geopolitical reasons. In 2022, Western sanctions crushed Russia’s MC-21 program. While Russia is russifying the aircraft with Russian-made components, the resulting aircraft will be a very different jet.

The MC-21 is now inefficient, heavy, and has no prospect of gaining EASA or FAA type certification any time soon, if ever. All this means that while the Boeing 737 and even the A320, by comparison to the MC-21 and C919, may be a bit squishy, they continue to set the industry standard for six-abreast narrowbody aircraft. They will likely continue to do so until their replacements arrive in the 2030s.