in 2025 the subject of "worth it" means much more than the value of the "hard product" or the "soft product"
30 years of confusion and uninformed declarations about "shrinking seats" makes the discussion difficult
so in order to have that discussion i need to baseline a few topics....
first is seat width
airlines are not shrinking the width of seats
let's get this out of the way......
in the united states 90% of our air travel, both domestic and international, takes place on 73X or A32X metal flown by american, delta, southwest or united i.e. the us big 4
subsidiaries that fly other metal (bombardier/airbus, embraer & canadair i.e. regional jets), allegiant with their almost dead MD8X fleet, 'new' carriers like jsx, avelo, etc. are not part of this discussion
2-aisle widebodies and long-range service will be added to the discussion later......
the single-aisle boeing family, the 707, 727, 737 and 757, were all built from the same tooling, and the upper half of the hull is the same for all 4 aircraft: at floor level the internal width of the cabin is 139" and it's been that way since the 707-120 first flight in 1957
the single-aisle airbus family i.e. the a320/19/21/neo/xlr/etc. in the same way have never varied in hull cross-section: at floor level the internal width of the cabin is 146" and it's been that way since the a320 first flight in 1987
for avoidance of doubt, all single-aisle boeing and all single-aisle airbus aircraft have always been configured with 6 seats in each row in the back
maximum seat width is a function of the seat design and the space available to use for seats factoring the FAA regulation on Minimum Passenger Aisle Width (14 CFR 25.815):
'for aircraft with a seating capacity of 20 or more, the minimum passenger aisle width is 15 inches at less than 25 inches from the floor and 20 inches at 25 inches and more from the floor'
thus the total available space for 6 seats, including armrests is 124" for the 73X and 131" for the a32X
'armrest widths being equal' there is 1.16" per seat of additional possible width on an a32X
'if there were no armrests' the maximum possible seat widths are:
73X: 20.66"
a32X: 21.83"
'seat width' is NOT regulated by the faa and the distance 'between the armrests' to measure seat width is an assumed convention
before we continue, please peruse the following (plaintext spoiled for your convenience)
https://www.cbsnews.com/news/airline-seat-size-faa-complaints/
the below is linked from within the cbs article
it's a pdf that does not format well in plaintext but is still spoiled below, reads easier if you open the url:
https://img1.wsimg.com/blobby/go/2b7ac7a8-3914-4be3-a69a-dbd59cb43a84/downloads/FRO Seat Size Presentation Background Info 7.2.pdf?ver=1665350138871