シート幅 (Seat Width)

シート幅とは？

Seat width is the horizontal measurement of the usable seat cushion surface between the inner edges of the armrests. Unlike seat pitch, which measures fore-aft space, seat width determines how much shoulder and hip room each passenger has. It is measured in inches and is the second most important comfort metric in economy cabin design. Seat width is primarily constrained by aircraft fuselage diameter and the number of seats configured per row.

胴体幅とシート幅の関係

The interior cabin width of an aircraft — the distance between the inner faces of the fuselage frames — is fixed at design. Airlines configure their seat count per row within that fixed width. A wider fuselage (wide-body aircraft) accommodates more seats per row and/or wider individual seats than a narrow-body.

• Narrow-body (e.g., Boeing 737, Airbus A320): Interior cabin width approximately 141–148 inches (358–376 cm). Standard 3-3 layout yields seat widths of 16.6–18.0 inches each.
• Wide-body (e.g., Boeing 787, Airbus A350): Interior widths of 214–219 inches (544–556 cm). A 3-3-3 economy layout produces seat widths of 17–18 inches; a 3-3-3 vs. 2-4-2 choice dramatically changes each seat's width.
• Airbus A380: 220.5-inch main deck interior enables 10-abreast (3-4-3) at 17.8 inches per seat, or 9-abreast (3-3-3) at 19.5 inches — a meaningful difference for a 14-hour flight.

機種・クラス別の一般的な範囲

Economy seat widths on major carriers range from 16.1 inches (on 10-abreast Boeing 777 configured by some ultra-dense operators) to 18.5 inches on less-dense configurations. The FAA and EASA impose no minimum seat width regulation, leaving it entirely to airline discretion. Consumer advocacy groups have proposed a minimum of 17 inches, but no rule exists as of 2025.

Business class seat widths vary enormously: a forward-facing recliner may be 20–22 inches wide, while a full flat-bed suite (e.g., Qatar Airways QSuite) can be 26–28 inches wide when the partition is folded.

主な事例

The Boeing 777-200ER operated in 10-abreast economy (3-4-3) by some budget carriers offers seat widths as narrow as 16.1 inches — significantly below the 17-inch threshold. In contrast, the same aircraft configured 9-abreast (2-5-2 or 3-3-3) increases seat widths to 18–19 inches. The Airbus A350-900, with its wider fuselage and typical 9-abreast configuration, offers economy seats of 18–18.5 inches — considered among the most comfortable in long-haul economy. The Embraer E175, a regional jet, offers a remarkable 2-2 layout with 17.8-inch seats, wider than many widebody economy seats.

関連コンポーネント

Seat width interacts with seat pitch to define total passenger space. Airlines choosing between narrow and wide seat configurations must balance seat width against row count and total revenue. The cabin class tier determines the allocated floor area per passenger, directly constraining achievable seat widths. In the galley and lavatory design phase, engineers account for the total passenger count — itself a function of seat width decisions — to size the service infrastructure appropriately.