Square Footage Calculator

Square footage is the most fundamental measurement in real estate, home improvement, and construction. Whether you're calculating flooring materials, determining if furniture will fit, comparing home sizes, or estimating project costs — accurate area measurement is the starting point.

Real estate vs. interior measurement: real estate square footage typically measures to the outside of exterior walls and includes all finished living areas above grade. Garages, unfinished basements, and attic space are generally excluded from "living area" measurements. Interior square footage (what you'd measure for flooring) is smaller because it's measured to the inside of the walls and excludes wall thickness (~6 inches per side, or ~1 foot per direction in a typical room).

Standard room size reference: Bathroom: 40–100 sq ft. Bedroom: 100–200 sq ft. Kitchen: 100–200 sq ft. Living room: 250–400 sq ft. Master bedroom: 200–300 sq ft. Average US home: 2,300 sq ft (2023 Census data).

For irregular rooms: break the space into regular shapes (rectangles, triangles, circles) that together cover the entire area. Calculate each sub-shape separately and sum the results. An L-shaped room is simply two rectangles; a room with a bay window adds a rectangular protrusion; a curved sunroom section can be approximated as a portion of a circle or series of rectangles.

Home improvement cost estimating: once you know square footage, you can estimate materials costs quickly. Multiply by standard material rates: hardwood flooring ($5–$15/sq ft), luxury vinyl plank ($2–$7/sq ft), tile ($3–$15/sq ft), carpet ($1–$5/sq ft), paint ($0.10–$0.25/sq ft for one coat). Add 10–20% for materials waste and installation complexity.