What Is the Sofa Size Calculator?
The Sofa Size Calculator helps you choose a couch that fits your living room without overwhelming or underfilling the space. A common interior-design guideline is that a sofa should span roughly two-thirds to three-quarters of the wall it sits against. This tool uses 75% as the recommended width, then estimates how many people can comfortably sit on it and how much floor clearance remains.
How to Use It
Measure the width of the wall or area where the sofa will go, in inches, and enter it as the Room Width. Then set the Width Per Seat — most cushions are about 22–26 inches wide, with 24 inches a solid default. The calculator instantly returns the recommended sofa width, the estimated seat count, and the leftover clearance you'll have on either side.
The Formula Explained
The recommended width is simply $$\text{Sofa Width} = 0.75 \times \text{Room Width}$$ The seat count is the sofa width divided by your per-seat width, rounded down to a whole number: $$\text{Seats} = \left\lfloor \frac{\text{Sofa Width}}{\text{Seat Width}} \right\rfloor$$ The clearance is whatever is left of the room width after the sofa: $$\text{Clearance} = \text{Room Width} - \text{Sofa Width}$$ That clearance accounts for side tables, walkways, and breathing room.
Worked Example
Suppose your room wall is 144 inches (12 ft) wide and you want 24-inch seats. The recommended sofa width is $$144 \times 0.75 = \mathbf{108 \text{ inches}}$$ Seats = \(\left\lfloor 108 / 24 \right\rfloor = \mathbf{4}\) seats. Clearance = \(144 - 108 = \mathbf{36}\) inches of remaining space. A 108-inch sofa with 36 inches to spare leaves comfortable room on both sides.
FAQ
Should a sofa really be 75% of the room? It's a guideline for visual balance. Designers often cite a range of 66%–75% of the wall length; choose lower for a roomier feel.
How wide is one sofa seat? Typically 22 to 26 inches per cushion. Use a larger number for deep, plush sofas and a smaller one for compact apartment styles.
What about depth and walkways? This tool focuses on width. Leave at least 18 inches between the sofa and a coffee table and 30–36 inches for main walkways.
