Square footage is the starting number for flooring, carpet, paint, roofing, sod, heating and cooling estimates, and for comparing homes and rental prices. Real rooms are rarely a single rectangle, so this calculator lets you break a space into up to four simple shapes — rectangles, triangles, circles and trapezoids — and adds them up, with an optional waste allowance and cost estimate.
How to use the square footage calculator
- Choose the number of areas (1 to 4) and the unit you measured in.
- For each area, pick a shape and enter its dimensions.
- Optionally add an extra for waste percentage — useful when buying flooring or sod.
- Enter a price per square foot to estimate the cost, or clear it to skip.
- Read the total on the tape and the breakdown in the table below.
Square footage formulas
If you measured in another unit, the calculator converts at the end: square inches ÷ 144 = square feet, square yards × 9 = square feet, and square meters × 10.764 = square feet.
Worked example: an L-shaped living room
Split the L into a 14 × 12 ft main area and a 10 × 8 ft alcove.
Area 1: 14 × 12 = 168 ft² · Area 2: 10 × 8 = 80 ft²
Total: 168 + 80 = 248 ft² (23.04 m²). At $4.50 per square foot, the material costs about $1,116.
Adding 10% for waste raises the order to 272.8 ft², or about $1,227.60.
Measuring irregular spaces
- Split, don’t estimate. Divide the floor into rectangles first, then handle angled walls or bays as triangles or trapezoids.
- Subtract what you won’t cover. For flooring, kitchen islands and built-in cabinets are usually left out; calculate them as separate areas and subtract.
- Measure at floor level to the wall, ignoring baseboards, and round each measurement up to the next inch.
- Use the feet-and-inches tool if you need to add or convert tape-measure readings first: the feet and inches calculator turns 12’ 7 1/2” into decimal feet.
Square footage in real estate
When a listing says a house has 2,000 square feet, it usually means finished living area measured to the outside of exterior walls, under the ANSI Z765 standard many US appraisers follow. That standard counts finished, heated space above grade, requires most of a room to have a ceiling of at least 7 feet, and lists garages, unfinished spaces and basements separately. Because builders, appraisers and tax assessors do not always follow the same rules, a home’s square footage can differ between documents by a surprising amount. Price per square foot is a handy comparison, but only when both homes were measured the same way.
Area unit equivalents
| Unit | Square feet |
|---|---|
| 1 square inch | 1/144 ft² (0.00694) |
| 1 square yard | 9 ft² |
| 1 square meter | 10.764 ft² |
| 1 acre | 43,560 ft² |
For flooring that comes in boxes, the tile calculator converts square footage into tiles and boxes, and the paint calculator handles walls and ceilings.
Frequently asked questions
How do I calculate the square footage of a room?
Measure the length and width in feet and multiply them. A room 14 feet by 12 feet is 168 square feet. If you measure in feet and inches, convert the inches to a decimal of a foot first — 12 ft 6 in is 12.5 ft.
How do I find the square footage of an L-shaped room?
Split the room into two rectangles that do not overlap, find each area, and add them. Enter each rectangle as its own area in the calculator and it totals them for you.
How do I convert square inches to square feet?
Divide by 144, because a square foot is 12 inches by 12 inches. For example, 2,880 square inches is 20 square feet. To go from square meters to square feet, multiply by about 10.764.
How much extra flooring should I buy?
Add about 5–10% for straight-laid flooring in simple rooms and 10–15% for diagonal or herringbone patterns, many corners, or materials that break easily. The extra covers cuts, mistakes and future repairs.
Does a home's square footage include the garage and basement?
Under the ANSI Z765 measuring standard used by many US appraisers, reported living area counts finished, heated space above grade. Garages, unfinished areas and below-grade basements are listed separately. Local real-estate practice can vary.