Sofa Size Calculator
A sofa that's too big crowds the room; one that's too small looks lost. Enter your wall length, room depth and how many people you want to seat to find the sofa width and depth that fit, with space left for a coffee table and walkways.
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How this calculator works
The calculator starts with the wall the sofa will sit against. It keeps at least 18 inches free at each end (24 inches if you want side tables), which sets the widest sofa the wall can take. It then aims for a sofa no wider than about two-thirds of the wall, which is the proportion designers use so the room looks balanced.
Next, it matches that to the number of seats you need: a loveseat for two is usually 52 to 64 inches, a three-seater 72 to 90 inches, and a four-seater 90 to 108 inches.
For depth, it allows 16 inches between the sofa and coffee table, 24 inches for the table itself and 36 inches for a walkway, plus 36 inches behind the sofa if it floats in the room. Whatever depth is left over is the deepest sofa that fits.
Tips for a better result
Measure the wall and then the way in
Get the wall length first, then measure every door, hallway and stair turn between the front door and the room. A sofa that suits the wall perfectly is no use if it cannot get up the stairs.
Look at seat depth as well as overall depth
Two sofas with the same overall depth can feel very different. A deep, low sofa with big arms uses a lot of floor for the seating it gives you. Check the seat width between the arms, not just the outside measurement.
Allow for arms and cushions
Roll arms and tall back cushions add inches that the label often leaves out. Work from the manufacturer’s overall width, and if you are close to your maximum, choose a sofa with slimmer arms.
Check the legs and the light
A sofa on raised legs looks lighter and lets you see the floor underneath, so it can feel smaller in a compact room than a skirted sofa of the same width.
Limitations of This Estimate
The calculator treats the room as a simple rectangle and the sofa as a straight, three-sided box. L-shaped sectionals, chaise ends and curved sofas take up floor space in a different way, so use the width of the longest side as a starting point and mark the full footprint on the floor with tape.
It also does not know where your doors, radiators or windows are. Check that a door can still swing fully open and that nothing blocks a heater or vent.
Frequently Asked Questions
Most 12 × 12 rooms suit a three-seater sofa 72 to 90 inches wide. Keep it to no more than about two-thirds of the wall (96 inches on a 12-foot wall), with at least 18 inches free at each end. In front of the sofa, allow around 76 inches for a coffee table and a walkway.
Usually 72 to 90 inches (183 to 229 cm) from arm to arm. A loveseat is about 52 to 64 inches, and a four-seater about 90 to 108 inches. Arm width varies a lot, so check the seat width as well as the overall width.
14 to 18 inches, with 16 inches being ideal. That's close enough to reach a drink from the sofa and far enough to walk past without knocking your knees.
Measure the inside of the door frame (width and height), plus every hallway, stair turn and doorway on the way in. A sofa usually fits if its depth or height is less than the door width. If its diagonal depth is less than the door height, it can usually be tilted through. Our Furniture Fit Calculator checks this for you.
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