How this calculator works
Choosing a sofa size starts with how many people you want to seat comfortably and how much wall space you actually have. Standard sofa cushions average 22 to 26 inches wide per seat, so multiplying that by your desired seat count gives a good estimate of the total sofa length you need.
A common interior design guideline is to keep furniture at or under about three-quarters of the available wall length, leaving room for walkways, outlets, and a balanced look. This calculator compares your needed sofa length to that recommended maximum for the wall you entered.
This is a general planning guideline; always check a specific sofa’s listed dimensions and leave clearance for doors and walkways before buying.
Last reviewed August 2026