The Story Behind This Sofa
Seater counts are less precise than buyers assume, and it is worth knowing how they are actually arrived at.
A sofa is described by how many cushion positions it has, not by how many people can physically sit on it. A three-cushion sofa is a three seater even if it is long enough for four, because the fourth person would have to sit across a join - uncomfortable, and it looks wrong. Conversely a single bench seat of the same length has no joins at all, so it genuinely flexes: three people in comfort, four when the family arrives.
Seat width per person is the number that actually matters. Comfortable is around 22 to 24 inches each; anything under about 20 becomes tight for adults. Multiply by the seats you want, add the arm widths, and you have your minimum sofa length - which is exactly the calculation we run when someone tells us they want a seven seater in a room that will not take one.
Bench seats also wear more evenly, because people do not always sit in the same three spots.