What is an area calculator?
An area calculator works out how much flat surface a shape or a piece of land covers. Choose a shape, type its length, width, radius or sides, and the calculator shows the answer in the unit you used plus square feet, square metres, square yards, acres, hectares, cents and guntha. Use it for land and plots (it is an area calculator for land first), for a room's flooring and paint, or a quick check for geometry homework. It is free, needs no download and works on any phone.
What is area?
Area is the amount of two-dimensional space inside a closed shape. It is measured in square units: a square 1 foot long on each side has an area of 1 square foot (1 sq ft). If you measure in metres, the answer is in square metres (m²); in inches, square inches; in millimetres, mm². Area is different from perimeter, which is the distance around the edge, and from volume, which measures three-dimensional space (see our volume calculator).
How to use the area calculator
- Choose the shape – square, rectangle, triangle, circle, trapezoid, parallelogram, ellipse, or a plot with 4 different sides.
- Choose the unit – feet, metres, inches, yards, cm, mm or km. All dimensions must use the same unit. For feet and inches, convert inches to decimal feet first: 10 ft 6 in = 10.5 ft (divide the inches by 12).
- Enter the dimensions. The result shows the area, the formula with your numbers, the perimeter where it applies, and every common land unit.
Area formulas for every shape
| Shape | Area formula | Example |
|---|---|---|
| Square | side × side = s² | s = 20 ft → 400 sq ft |
| Rectangle | length × width | 40 × 30 ft → 1,200 sq ft |
| Triangle | ½ × base × height | b = 12, h = 8 → 48 |
| Triangle (3 sides) | √(s(s − a)(s − b)(s − c)), s = (a + b + c) ÷ 2 | 13, 14, 15 → 84 |
| Circle | π × r² | r = 7 → 153.94 |
| Trapezoid / trapezium | ½ × (a + b) × h | a = 10, b = 6, h = 8 → 64 |
| Parallelogram | base × height | b = 12, h = 8 → 96 |
| Ellipse | π × a × b | a = 5, b = 3 → 47.12 |
| Quarter circle | π × r² ÷ 4 | r = 7 → 38.48 |
In every formula the “height” is the perpendicular distance, not a slanted side. For a circle, if you know the diameter, halve it to get the radius.
How to calculate the area of a triangle
If you know the base and the perpendicular height, multiply them and halve the result: a triangle with base 12 m and height 8 m covers ½ × 12 × 8 = 48 m². If you only know the three sides, use Heron’s formula. For sides 13, 14 and 15: s = 21, and area = √(21 × 8 × 7 × 6) = √7,056 = 84 square units. For a right-angled triangle, the two shorter sides are the base and height; our Pythagorean theorem calculator finds a missing side.
How to calculate the area of a rectangle and square
Multiply length by width. A room 14 ft by 12 ft has an area of 168 sq ft; a square plot of 20 ft per side is 400 sq ft. For a room that is not a simple rectangle, split it into rectangles, calculate each one, and add them.
Area calculator for land with 4 different sides
Real plots are rarely perfect rectangles. A four-sided plot with four different sides cannot be measured from the sides alone, because the same four sides can form many shapes with different areas. Measure one diagonal as well. The diagonal splits the plot into two triangles, and Heron’s formula gives the area of each. Select “Plot with 4 different sides + diagonal”, enter sides a, b, c, d and the diagonal, and the calculator adds the two triangles for you.
Example: sides 13, 14, 15 and 12 ft with an 18 ft diagonal. Triangle (13, 14, 18) ≈ 90.4 sq ft and triangle (15, 12, 18) ≈ 89.3 sq ft, so the plot is about 179.7 sq ft. For irregular shapes with more sides, divide the land into triangles from one corner, measure each diagonal, and add the triangle areas. An area calculator on a map or GPS app gives a rough figure, but a tape-and-diagonal survey or official records are more reliable for buying land.
How to calculate area of land in India
In India, plots are usually sold in square feet or square yards (gaj) in cities, and in acres, hectares, bigha, guntha, cents or marla in rural areas. This land area calculator India section shows the standard conversions.
| Unit | In square feet | Where it is used |
|---|---|---|
| 1 square metre | 10.764 sq ft | Everywhere, official records |
| 1 square yard (gaj) | 9 sq ft | North India urban plots |
| 1 cent | 435.6 sq ft | Kerala, Tamil Nadu, Andhra Pradesh |
| 1 guntha | 1,089 sq ft | Maharashtra, Karnataka, Telangana, Gujarat |
| 1 marla | 272.25 sq ft (can vary) | Punjab, Haryana, Himachal |
| 1 kanal | 20 marla ≈ 5,445 sq ft | Punjab, Haryana, J&K |
| 1 acre | 43,560 sq ft = 4,046.86 m² | All India |
| 1 hectare | 1,07,639 sq ft = 2.471 acres | All India, government records |
Bigha and katha vary by state
There is no single national value for a bigha. It is roughly 14,400 sq ft in West Bengal and Assam, around 27,000 sq ft (pucca bigha) in parts of Rajasthan, Uttar Pradesh and Bihar, and only about 9,000 sq ft in Punjab and Haryana; even districts within one state can differ. Katha, biswa and dismil vary in the same way. Always confirm the local value with the tehsil or revenue office, or the land record (jamabandi, 7/12 extract, khatauni), and then divide the square-feet result from this calculator by that value.
Unit conversions for area
- 1 sq m = 10.764 sq ft; 1 sq ft = 0.0929 sq m
- 1 sq ft = 144 sq in; 1 sq yd = 9 sq ft
- 1 acre = 0.4047 hectare; 1 hectare = 2.471 acres
- 1 sq km = 100 hectares = 247.1 acres
- 1 sq m = 10,000 cm² = 10,00,000 mm²
Remember to square the conversion factor. Because 1 m = 3.281 ft, 1 m² = 3.281² ≈ 10.764 sq ft, not 3.281.
Practical uses
- Flooring and tiles – calculate the room area in sq ft and add 5–10% for cutting waste.
- Painting – wall area = wall length × height, minus doors and windows.
- Land and property – check a builder’s carpet area or a plot size before buying. Use the percentage calculator to compare carpet area with super built-up area.
- Gardening and fencing – area tells you how much soil, grass or fertiliser to buy; perimeter tells you how much fence you need.
How to find area: calculator formula quick reference
How to find area with a calculator: pick the shape, enter its dimensions and read the result in several units. The area calculator formula for each shape is: square s², rectangle l × w, triangle ½ × b × h, circle πr², trapezoid ½(a + b) × h, parallelogram b × h, ellipse π × a × b.
Area calculator in feet and inches
For an area calculator with feet and inches, turn each measurement into decimal feet first: inches ÷ 12. A room of 12 ft 6 in × 10 ft 3 in is 12.5 × 10.25 = 128.13 sq ft. Or convert everything to inches and choose the inches unit: 150 × 123 = 18,450 sq in, and dividing by 144 gives the same 128.13 sq ft. That is how the area calculator feet and inches method works for flooring and tiles.
Area calculator in inches, mm and square meters
Choose inches or mm in the unit box to work with small parts: a 210 × 297 mm A4 sheet is 62,370 mm², or 0.0624 m². The area calculator in square meters converts any unit: 1 m² = 10.764 sq ft = 1,550 sq in = 1,000,000 mm².
Area calculator in km² for large regions
Choose kilometres for large areas. A region 12 km × 8 km is 96 km², which is 9,600 hectares. 1 km² = 100 hectares = 247.1 acres.
Area calculator and converter
This area calculator and converter shows the result in square feet, square metres, square yards, acres and hectares together, so you do not need a separate area calculator converter. Use the unit converter for other units.
Area calculator for a quadrilateral with four different sides
For a quadrilateral, the calculator needs more than four sides, because four sides alone can form many shapes with different areas. Measure one diagonal as well. For a plot with four different sides, the area calculator for land splits it along that diagonal into two triangles and adds their areas with Heron's formula. The land area calculator formula for each triangle is √(s(s − a)(s − b)(s − c)), where s is half the perimeter.
Area calculator with dimensions of an L-shaped room
Split the shape into rectangles. An L-shaped room 20 × 12 ft with a 8 × 6 ft cut-out is 240 − 48 = 192 sq ft. Enter each rectangle's dimensions in turn and add the areas.
Area calculator se jameen kaise nape
Jameen kaise nape? Plot ki chaaron bhujaayein aur ek vikarn (diagonal) naap lein, feet ya metre mein. Upar "Plot with 4 different sides + diagonal" chunein aur maap bharein. Area calculator se jameen ka kshetrafal sq ft, gaj aur acre mein mil jaata hai. Bigha aur katha har rajya mein alag hote hain.
Area calculator for Nepal land units
In the hill regions of Nepal, 1 ropani = 16 aana = 5,476 sq ft (about 508.7 m²), and 1 aana = 342.25 sq ft. In the Terai, 1 bigha = 20 kattha = 72,900 sq ft (about 6,772.6 m²). To use the area calculator for Nepal, find the area in sq ft and divide by 5,476 for ropani or by 342.25 for aana.
Area calculator from image or using camera
Phone apps that measure an area from an image or using the camera (augmented reality) give a quick estimate, but they can be off by several per cent. For buying land, flooring or paint, measure with a tape and enter the numbers here.
Volume calculator: area × height
Once you know the area of a base, volume = area × height. A 10 × 8 ft floor with 9 ft walls holds 80 × 9 = 720 cubic feet. The volume calculator does this for common solids.
Area calculator in Java
An area calculator in Java is a switch on the shape: case "circle": area = Math.PI * r * r; break; case "rectangle": area = l * w; break;. Use doubles and Math.PI rather than 3.14 for accuracy.
Frequently asked questions
How is area calculated?
Area is calculated with a formula for each shape: length × width for a rectangle, ½ × base × height for a triangle, π × r² for a circle and ½ × (a + b) × h for a trapezoid. The answer is in square units.
How do I calculate the area of land with 4 different sides?
Measure the four sides and one diagonal. The diagonal splits the plot into two triangles; find each area with Heron’s formula and add them. Choose the 4-sided plot option in the calculator to do this automatically.
How do I calculate area in square feet from feet and inches?
Convert inches to feet by dividing by 12 (for example, 12 ft 6 in = 12.5 ft), then multiply length by width. A room 12.5 ft by 10 ft is 125 sq ft.
How many square feet are in an acre?
One acre is 43,560 square feet, which equals 4,046.86 square metres or 0.4047 hectare.
How many square feet is one bigha?
It depends on the state. A bigha is about 14,400 sq ft in West Bengal and Assam, around 27,000 sq ft in parts of Rajasthan and Uttar Pradesh, and roughly 9,000 sq ft in Punjab and Haryana. Check the local revenue office value.
How do I calculate the area of a circle?
Multiply π (about 3.1416) by the radius squared. A circle with a 7 m radius has an area of about 153.94 m². If you have the diameter, halve it first.
How do I find the area of an irregular shape?
Split the shape into rectangles and triangles, calculate each piece with this area calculator, and add the results. For curved edges, approximate with several small triangles.
Is this area calculator free to use?
Yes. The area calculator is free, needs no app download, and works on mobile and desktop.
How do I calculate area in feet and inches?
Convert inches to feet by dividing by 12, then multiply length by width. 10 ft 6 in × 8 ft = 10.5 × 8 = 84 sq ft.
How many square feet are in 1 ropani?
1 ropani is 5,476 sq ft, about 508.7 square metres.
Last updated 2026-09-18