Square Footage Calculator
Find the area of a room, floor or plot in square feet, square metres and more. Advanced adds other shapes, several rooms, cut-outs, waste, cost and boxes to buy.
For an odd-shaped room, split it into rectangles and add each one. Take away things you won't cover, like a kitchen island or a fireplace hearth.
Flooring and tiles: about 5–10% for a straight lay, 15% or more for diagonal or herringbone.
Printed on the box. Gives the number of boxes to buy.
How your area is worked out
Area = length × width for each rectangle; other shapes have their own rule.
- 1
Measure the area
12 ft × 10 ft= 120 sq ft
- 2
Add them up
One area only= 120 sq ft
- 3
Allow for waste
No waste added= 120 sq ft
- 4
In other units
120 ÷ 10.7639= 11.15 m²
Read more: the formulas for every shape, a worked example and land units
Square footage is how many 1 ft × 1 ft squares fit on a floor. For a rectangle you multiply the length by the width. Other shapes have their own rule, and an odd-shaped room can be split into rectangles that you add together. Work in one unit at a time: feet give square feet, metres give square metres.
The formula
rectangle = length × width
square = side × side
circle = π × (diameter ÷ 2)²
part of a circle = π × radius² × angle ÷ 360
triangle = ½ × base × height
triangle from 3 sides = √(s(s − a)(s − b)(s − c)), s = (a + b + c) ÷ 2
trapezoid = (top + bottom) ÷ 2 × height
L-shape = full length × full width − cut-out length × cut-out width
border = (length + 2 × border)(width + 2 × border) − length × width
ring = π × ((diameter ÷ 2 + border)² − (diameter ÷ 2)²)
oval = π × long way × short way ÷ 4
total = areas added − areas taken away
to buy = total × (1 + waste % ÷ 100)
cost = area to buy × price per area + fixed cost
Worked example
A room 12 ft long and 10 ft wide is 12 × 10 = 120 sq ft. One square metre is 10.7639 sq ft, so that is 120 ÷ 10.7639 = 11.15 m². One square yard is 9 sq ft, so it is 120 ÷ 9 = 13.33 sq yd, and one acre is 43,560 sq ft, so it is 0.00275 acres.
Now add a hallway 8 ft × 5 ft twice (80 sq ft) and take away a 4 ft × 3 ft kitchen island (12 sq ft): 120 + 80 − 12 = 188 sq ft. With 10% extra for waste, buy 188 × 1.1 = 206.8 sq ft. At $3 per sq ft plus $100 for fitting, the cost is 206.8 × 3 + 100 = $720.40. If one box covers 20 sq ft, you need 206.8 ÷ 20 = 10.34, so 11 boxes.
Feet and inches
Turn the inches into part of a foot before multiplying: 12 ft 6 in is 12 + 6 ÷ 12 = 12.5 ft. A room 12 ft 6 in × 10 ft is 12.5 × 10 = 125 sq ft. Don't multiply 12.6 by 10; 6 inches is half a foot, not 0.6.
Area units
| Unit | Equals | Used in |
|---|---|---|
| 1 square foot | 144 sq in = 0.092903 m² | US, UK, India, Gulf property |
| 1 square metre | 10.7639 sq ft | Most countries |
| 1 square yard | 9 sq ft = 0.836127 m² | Carpet in the US and UK |
| 1 gaj (India, Pakistan) | 1 sq yd = 9 sq ft | Plots in north India and Pakistan |
| 1 cent (South India) | 1/100 acre = 435.6 sq ft | Kerala, Tamil Nadu, Karnataka plots |
| 1 tsubo / pyeong (Japan, Korea) | 3.3058 m² = 35.58 sq ft | Flats and land in Japan and Korea |
| 1 acre | 43,560 sq ft = 4,046.86 m² | Land in the US, UK, India |
| 1 hectare | 10,000 m² = 2.4711 acres | Land in most countries |
Local land units like the bigha, kanal and marla change size from state to state, so they are not used here. Check the local value before converting.
Tips for measuring a room
- Measure wall to wall at floor level, and round up to the next inch or centimetre.
- Include closets and alcoves you want covered; add them as their own small rectangles.
- For a bay window or a curved wall, add part of a circle (a half circle is 180°).
- Carpet and vinyl come in fixed roll widths, so you may need more than the floor area; ask the shop to plan the seams.
The waste percentages are common rules of thumb from flooring fitters, not fixed rules; follow the maker's advice for your product. The oval perimeter uses Ramanujan's close approximation. Unit sizes are exact by definition (1 ft = 0.3048 m). Checked on 10 October 2026.
Common questions
How do I calculate square footage?
Multiply the length by the width in feet. A room 12 ft long and 10 ft wide is 12 × 10 = 120 sq ft. For odd shapes, split the room into rectangles and add them up, or take away cut-outs such as a kitchen island.
How do I calculate square feet with feet and inches?
Turn the inches into part of a foot first by dividing by 12. 12 ft 6 in is 12.5 ft, so a 12 ft 6 in × 10 ft room is 125 sq ft. Don't multiply 12.6 by 10, because 6 inches is half a foot, not 0.6.
How many square feet are in a square metre?
One square metre is 10.7639 sq ft, so 120 sq ft is 11.15 m². One square yard is 9 sq ft and one acre is 43,560 sq ft. The calculator shows your area in all of these units at once, so there's no need to convert by hand.
How much extra flooring should I buy for waste?
A common rule of thumb is about 10% extra. A 188 sq ft floor with 10% waste needs 206.8 sq ft, which is 11 boxes if one box covers 20 sq ft. Waste figures are rules of thumb, so follow the maker's advice for your product.
How do I find the area of a circle or an L-shaped room?
For a circle, area = π × (diameter ÷ 2)². For an L-shape, take the full length × full width and subtract the cut-out length × cut-out width. Pick the shape in the calculator and it does the sum for you.
How many square feet is a gaj or a cent?
A gaj, used for plots in north India and Pakistan, is 1 square yard or 9 sq ft. A cent, used in Kerala, Tamil Nadu and Karnataka, is 1/100 acre or 435.6 sq ft. Bigha, kanal and marla change from state to state, so they're not used here.
Related calculators
Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.