Sofa Size Calculator — What Size Sofa Fits My Room?
Not sure what size sofa will fit your living room? Enter the room length and width, how many people need to sit, and the minimum walking clearance you want on each side. The calculator applies the designer two-thirds rule and seat-width standards to recommend a length and depth that keeps your room balanced and navigable.
Measurement unit
cm
cm
people
cm
Based on seating capacity and 2/3-of-wall rule with clearance
- 1
Longer wall (sofa side)
max(400, 350) = 400 - 2
Clearance limit
400 − 2 × 45 = 310 - 3
Two-thirds rule limit
400 × 2 ÷ 3 = 266.7A sofa should occupy no more than two-thirds of its wall to keep the room balanced. - 4
Seat-based target
3 × 55 + 20 = 185 - 5
Recommended length
min(min(310, 266.7), 185) = 185
How does this calculator work?
A sofa should be at most two-thirds of its wall and leave at least 45 cm (18 in) of clearance on each side. Max sofa length = min(wall − 2 × clearance, wall × 2/3). Allow about 55 cm per seat plus 20 cm for arms. Depth should be ≤ 90 cm and leave room for a coffee table and walking clearance in front.
Formula
How this is calculated
Interior designers typically follow the "two-thirds rule": a sofa should be no longer than two-thirds of the wall it sits against, so the room does not feel dominated by the piece. A second constraint is practical: leave at least 45 cm (18 in) on each side of the sofa for circulation, and at least 40–50 cm between the sofa and a coffee table in front. This calculator enforces both constraints and returns the tighter of the two limits as the maximum recommended length.
Seat width varies by style — a standard dining-chair-like seat is about 50 cm wide while a generous lounge seat can be 65 cm. This tool uses 55 cm per seat plus 20 cm for armrests as a typical average. The recommended depth (front-to-back) is capped at 90 cm — a common standard sofa depth — and further limited so that adequate clearance remains between the sofa's front edge and the opposite wall (allowing for a coffee table). If the room is narrow, a shallower loveseat or apartment-depth sofa around 75–80 cm may suit better.
Sofa type guidance: a loveseat is typically under 140 cm long (2 seats), a standard three-seater 140–200 cm, a four-seater up to 260 cm, and anything longer is sectional territory. The sofa footprint as a percentage of the room floor area is also shown — designers often aim to keep upholstered furniture below 20–25% of floor space for an airy feel.
Frequently asked questions
The two-thirds rule says that a sofa's length should be roughly two-thirds of the wall it is placed against. This proportion makes the piece look intentional and leaves enough open wall on either side to prevent the room from feeling cramped. It is a starting point, not a hard law — doorways, windows, and the overall room scale all matter.
Allow at least 40–45 cm (16–18 in) between the front edge of the sofa and a coffee table, and at least 90 cm (36 in) as a main traffic-flow corridor. If the sofa faces a TV, there should be at least 150 cm (about 5 ft) to the screen for comfortable viewing.
Standard sofas are 85–95 cm deep (front to back). For a small or narrow room, apartment-depth sofas at 75–80 cm work better, keeping more floor space visible and making the room feel larger. Very deep (100+ cm) sofas suit large open-plan spaces where comfort and scale take priority.
Also known as
TG we-Calculate Editorial Team. (2026). Sofa Size Calculator — What Size Sofa Fits My Room? [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/sofa-size-calculator
TG we-Calculate Editorial Team. "Sofa Size Calculator — What Size Sofa Fits My Room?." TG we-Calculate. 2026. https://we-calculate.com/calculator/sofa-size-calculator.
TG we-Calculate Editorial Team, "Sofa Size Calculator — What Size Sofa Fits My Room?," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/sofa-size-calculator
@misc{wecalculate_sofa_size_calculator, title = {Sofa Size Calculator — What Size Sofa Fits My Room?}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/sofa-size-calculator}}, year = {2026}, note = {TG we-Calculate} }
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