Square Footage Calculator
Compute the area of a rectangular room, lot, or floor plan in square feet from length and width in feet. Useful for flooring, paint, and rental listings.
Last updated: September 2026
Compare with similar
About this calculator
For a rectangular space, area = length × width. If both measurements are in feet, the result is in square feet — the standard unit used by US real-estate listings, flooring quotes, and interior paint estimates.
For non-rectangular spaces, split the floor plan into rectangles (or right triangles), calculate each piece, and add. For a right triangle, area = ½ × base × height. For a circular area (a round patio, for example), use π × r² — the standalone circle-area calculator handles that.
Two things trip up new users. First, always measure the same way twice: outside-to-outside for the footprint of a house, inside-to-inside for the space of a room. Second, when converting to square metres for international listings, multiply by 0.0929: 1000 sq ft ≈ 92.9 m².
How to use
Example — a 12-by-10 bedroom. Enter Length = 12 ft, Width = 10 ft. Result = 12 × 10 = 120 square feet. Enough for a queen bed (33 sq ft), two nightstands (~6 sq ft), a dresser (~10 sq ft), and clearance to walk around. Example — a 30-by-40 lot. Enter 30 and 40. Result = 1 200 square feet, which is roughly 0.0276 acres (an acre is 43 560 sq ft). For a whole-house floor plan, use the total outside dimensions; for a room, use wall-to-wall interior. If you are pricing flooring, add 10% for cutting waste, so a 120 sq ft room usually needs 132 sq ft of material ordered.
Frequently asked questions
How do I measure a non-rectangular room?
Divide the floor plan into rectangles and (if needed) right triangles. Compute each piece with length × width or ½ × base × height. Add them for the total. L-shaped rooms typically split cleanly into two rectangles along the inside corner. For irregular curves, approximate with several rectangles or use a laser measurer that reports area directly.
Do I include closets, alcoves, and stairwells?
It depends on the standard. Real-estate listings often quote 'gross living area' per ANSI Z765, which includes finished heated spaces (closets yes, garage no, unfinished basement no). For flooring or paint, measure the exact surface being covered — so exclude the stairwell if you are ordering wood flooring, include it if you are painting.
How do I convert to square metres?
Multiply square feet by 0.0929 (or divide by 10.764). 100 sq ft ≈ 9.29 m²; 1000 sq ft ≈ 92.9 m². For an average US 2000 sq ft home, the metric equivalent is about 186 m².
How does square footage relate to price per sq ft?
Price per sq ft = sale price / gross living area. It is the standard normalization for comparing homes of different sizes in the same neighborhood. To dig into a specific comp, feed the price and area into the property-tax calculator at /en/calculators/real-estate/property-tax/ or the home-affordability calculator at /en/calculators/real-estate/home-affordability/ to see monthly cost implications.