How to use this square footage calculator
- Pick the shape that matches the space: rectangle, circle, triangle or L-shape.
- Choose your unit and enter the measurements. Use “Feet + inches” to type a length like 11 ft 9 in without converting it.
- Add other rooms (optional): open “Add more rooms” to include up to three more rectangles or to repeat identical rooms, for a whole-floor total.
- Add extra and a price (optional) to see how much material to buy and what it may cost.
Square footage formulas for each shape
Area is always measured in square units. Work in feet and your answer is in square feet; work in meters and it is in square meters. Convert any inches to feet (divide by 12) before multiplying.
Rectangle or square
A = L × W
- L
- length (ft)
- W
- width (ft)
Example: a 12 × 15 ft bedroom is 12 × 15 = 180 sq ft. With inches, an 11 ft 9 in × 13 ft 4 in room is 11.75 × 13.3333 = 156.67 sq ft.
Circle
A = π × (d / 2)²
- d
- diameter, the distance straight across through the center (ft)
- π
- ≈ 3.14159
Example: a round patio 10 ft across has a radius of 5 ft, so its area is π × 5² = 78.54 sq ft. That is about 78.5% of a 10 × 10 ft square (100 sq ft).
Triangle
A = b × h / 2
- b
- base, any one side (ft)
- h
- height, measured at a right angle from the base to the opposite corner (ft)
Example: a triangular garden bed with a 12 ft base and 8 ft height is 12 × 8 ÷ 2 = 48 sq ft, half of the 96 sq ft rectangle around it.
L-shaped room
A = L₁ × W₁ + L₂ × W₂
- L₁ × W₁
- the main rectangle (part A)
- L₂ × W₂
- the section that sticks out (part B), measured only beyond part A
Example: part A is 20 × 12 ft = 240 sq ft and part B is 10 × 8 ft = 80 sq ft, so the room is 320 sq ft. The same idea works for any room with straight walls: split it into rectangles and triangles, then add the pieces.
Whole-house total
Add the rooms together. Three 11 × 12 ft bedrooms (396 sq ft), a 16 × 20 ft living room (320 sq ft) and a 12 × 14 ft kitchen (168 sq ft) come to 884 sq ft. In the calculator, set 3 identical areas for the bedrooms and enter the other two rooms as extra areas.
How to measure a room for square footage
- Sketch the floor plan on paper, even roughly. Mark doorways, closets and any bump-outs.
- Measure wall to wall at floor level with a tape measure or laser measure, along the longest straight runs. Write down feet and inches.
- Split odd shapes into rectangles, triangles and half-circles. Measure each piece separately so pieces do not overlap.
- Decide what to include. For flooring, include closets and any area the material will cover. Leave out areas under fixed cabinets or tubs if the floor will not go there.
- Add the pieces and, for materials, add an allowance for cuts and waste.
Metric tapes are fine too: a 4.2 × 3.6 m room is 15.12 sq m, or 162.75 sq ft. A home’s official size is a different question from the area of one floor. Fannie Mae requires appraisers to use the ANSI Z765-2021 measuring standard, which works from exterior measurements and counts finished areas above and below grade separately, so a listing may not match the sum of your room measurements.
Square feet to square meters, yards and acres
The conversions are exact: a foot is 0.3048 meter, so 1 sq ft = 0.3048² = 0.09290304 sq m; a yard is 3 feet, so 1 sq yd = 9 sq ft; and 1 acre = 43,560 sq ft.
| Square feet | Square yards | Square meters | Acres |
|---|---|---|---|
| 1 | 0.11 | 0.09 | 0.000023 |
| 10 | 1.11 | 0.93 | 0.00023 |
| 50 | 5.56 | 4.65 | 0.00115 |
| 100 | 11.11 | 9.29 | 0.0023 |
| 250 | 27.78 | 23.23 | 0.00574 |
| 500 | 55.56 | 46.45 | 0.0115 |
| 1,000 | 111.11 | 92.9 | 0.023 |
| 1,500 | 166.67 | 139.35 | 0.0344 |
| 2,000 | 222.22 | 185.81 | 0.0459 |
| 2,500 | 277.78 | 232.26 | 0.0574 |
| 5,000 | 555.56 | 464.52 | 0.115 |
| 10,000 | 1,111.11 | 929.03 | 0.23 |
| 43,560 | 4,840 | 4,046.86 | 1 |
| Square meters | Square feet | Square yards |
|---|---|---|
| 1 | 10.76 | 1.2 |
| 5 | 53.82 | 5.98 |
| 10 | 107.64 | 11.96 |
| 20 | 215.28 | 23.92 |
| 50 | 538.2 | 59.8 |
| 100 | 1,076.39 | 119.6 |
| 150 | 1,614.59 | 179.4 |
| 200 | 2,152.78 | 239.2 |
| 500 | 5,381.96 | 598 |
| 1,000 | 10,763.91 | 1,195.99 |
Cost by square foot: flooring example
Multiply the square footage (plus any extra for waste) by the price per square foot. The table below uses example prices only, not market data; flooring, labor and local prices vary widely, so use your own quotes in the calculator. Carpet is often priced per square yard; divide a per-square-yard price by 9 to get the price per square foot.
| Area | $2/sq ft | $4/sq ft | $6/sq ft | $8/sq ft | $10/sq ft |
|---|---|---|---|---|---|
| 100 sq ft | $200 | $400 | $600 | $800 | $1,000 |
| 150 sq ft | $300 | $600 | $900 | $1,200 | $1,500 |
| 200 sq ft | $400 | $800 | $1,200 | $1,600 | $2,000 |
| 300 sq ft | $600 | $1,200 | $1,800 | $2,400 | $3,000 |
| 500 sq ft | $1,000 | $2,000 | $3,000 | $4,000 | $5,000 |
| 1,000 sq ft | $2,000 | $4,000 | $6,000 | $8,000 | $10,000 |
| 1,500 sq ft | $3,000 | $6,000 | $9,000 | $12,000 | $15,000 |
| 2,000 sq ft | $4,000 | $8,000 | $12,000 | $16,000 | $20,000 |
Example: flooring for a 180 sq ft room with 10% extra is 198 sq ft; at an example price of $4 per sq ft that is $792.00.
What square footage is used for
Square footage drives most home project estimates: flooring, paint for ceilings, sod and mulch, and roofing or siding are all bought by area. For a concrete patio or slab, you need the area and the thickness; the concrete calculator turns those into cubic yards and bags. When you are shopping for a home, price per square foot is a quick way to compare listings, and the house affordability calculator shows what price range fits your budget. If your measurements are in fractions of an inch, the fraction calculator can add them up first.
Frequently asked questions
How do I calculate square feet?
Measure the length and width in feet and multiply them. A 12 ft by 15 ft room is 12 × 15 = 180 square feet. If a measurement includes inches, divide the inches by 12 first, so 11 ft 9 in becomes 11.75 ft. For odd shapes, split the space into rectangles, triangles and circles, find each area, and add them up.
How many square feet are in a square yard and a square meter?
A square yard is exactly 9 square feet, because a yard is 3 feet and 3 × 3 = 9. A square meter is about 10.7639 square feet, because a foot is defined as exactly 0.3048 meter, so one square foot is 0.09290304 square meter. To convert, divide square feet by 9 for square yards, or multiply by 0.0929 for square meters.
How many square feet is an acre?
An acre is 43,560 square feet, or about 4,047 square meters. To turn a lot size in square feet into acres, divide by 43,560: a 10,000 sq ft lot is 0.23 acre. An acre does not have a fixed shape; a square acre would be about 208.7 ft on each side.
How do I find the square footage of an L-shaped room?
Divide the L into two rectangles that do not overlap, find the area of each, and add them. For example, a 20 × 12 ft section plus a 10 × 8 ft section is 240 + 80 = 320 square feet. Measure the first rectangle across the full length of the room and the second only for the part that sticks out.
How much extra flooring should I buy?
Buy more than the room’s exact area, because boards and tiles are cut to fit at walls and some pieces are damaged or wasted. The right allowance depends on the material, the pattern and the room’s shape, so follow the manufacturer’s or installer’s instructions. This calculator lets you add any percentage: 10% extra on a 180 sq ft room means buying 198 sq ft.
Do closets and hallways count in a home’s square footage?
For flooring or paint, measure every area you will actually cover, including closets. For a home’s listed size, rules vary by source. Fannie Mae requires appraisers to follow the ANSI Z765-2021 standard, which measures finished above-grade area from the exterior and counts a level as below grade if any part of it is below grade. Tax records and listings may use other methods.