Square Footage Calculator
Calculate the area of any room, wall, yard or irregular space. Works in feet, metres and yards — then jump straight to paint, tile, drywall or flooring calculators.
How to Calculate Square Footage
For a rectangular room, multiply length × width — both in feet. A 12 ft × 10 ft room is 120 square feet. For irregular shapes, split the area into rectangles or simple shapes, calculate each one separately, then add them together. For circles, use π × radius². For triangles, use (base × height) / 2. If your measurements are in inches, divide the result by 144 to get square feet; if in metres, multiply sq m by 10.764.
What Counts as Floor vs Wall vs Yard Area?
Floor area = length × width of the room. Wall area = perimeter × ceiling height, minus door and window openings (subtract roughly 21 sq ft per door, 15 sq ft per window). Yard area includes everything inside your property boundary. Roof area on a pitched roof is larger than floor area — multiply by the pitch factor (1.06 for 4/12 pitch, 1.12 for 6/12, 1.20 for 8/12).
Common Uses for Square Footage
- Paint: one gallon covers ~350 sq ft — use our paint calculator
- Tile & flooring: order 10–15% extra for waste — see the tile calculator
- Drywall: one 4×8 sheet covers 32 sq ft — see the drywall calculator
- Marble/stone: use the marble calculator with slab size
- Wallpaper: convert to wall sq ft with our wallpaper calculator
- Topsoil / gravel: multiply by depth for volume — see the topsoil calculator or gravel calculator
- Roof materials: apply pitch factor, then use the roofing calculator