Area Calculator
- Length l = 6 ft and width w = 4 ft.
- Area A = l × w = 6 × 4 = 24 ft².
- Perimeter P = 2 × (l + w) = 2 × 10 = 20 ft.
- Diagonal d = √(l² + w²) = 7.2111 ft.
- 2,229,672.96 mm²
- 22,296.7296 cm²
- 2.2297 m²
- 3,456 in²
- 0.000550964 acres
- 0.000222967 hectares
- Area ÷ width = 6 ft, which matches the length entered.
Area Calculator: Find the Area of Common Shapes
This free area calculator works out the area of a rectangle, square, triangle, circle, trapezoid, parallelogram or ellipse, and the surface area of a cube. Choose a shape, type its measurements, pick a unit, and the area appears at once with the working, a diagram and the same area in other units. It is handy for floors, walls, gardens, plots of land, school geometry and quick material estimates.
Quick answer: a rectangle that is 6 feet long and 4 feet wide has an area of 24 square feet. The area of a circle with a 5 foot radius is 78.5398 square feet.
Area Formulas for Each Shape
Area measures the flat space inside a shape and is always given in square units, such as square feet or square metres. Every formula below is built into the calculator, and the table shows one worked example for each.
| Shape | Formula | Example | Area |
|---|---|---|---|
| Rectangle | length × width | 6 × 4 | 24 |
| Square | side × side | 5 × 5 | 25 |
| Triangle | ½ × base × height | ½ × 6 × 4 | 12 |
| Circle | π × radius² | π × 5² | 78.5398 |
| Trapezoid | ½ × (a + b) × height | ½ × (8 + 5) × 4 | 26 |
| Parallelogram | base × height | 7 × 4 | 28 |
| Ellipse | π × a × b | π × 6 × 4 | 75.3982 |
| Cube (surface) | 6 × edge² | 6 × 3² | 54 |
Rectangles, Squares and Parallelograms
For a rectangle, multiply length by width. A square is the same with equal sides. A parallelogram has the same area as a rectangle with its base and its straight-up height, which is why slanting a shape sideways does not change its area. If you are working out a room, remember to measure every wall and split an L-shaped floor into two rectangles. For a painting or concrete job, the paint calculator and concrete calculator start from the same area.
Triangles and Trapezoids
A triangle is exactly half of a rectangle with the same base and height, so its area is ½ × base × height. A trapezoid has two parallel sides. Its area equals the average of those two sides multiplied by the height. Both formulas need the height measured at a right angle to the base, not along a slanted edge.
Circles and Ellipses
A circle's area is pi times the radius squared, so doubling the radius makes the area four times as large. An ellipse is a stretched circle, and its area is pi times its two half-widths multiplied together. For radius, diameter, circumference and arc measurements, open the circle calculator.
Choosing Units and Converting Area
Always enter every measurement in the same unit. The result is shown in the matching square unit and in several others, plus acres and hectares for land. Keep in mind that one square metre is about 10.76 square feet, not 3.28, because both directions are converted. If you need to convert lengths on their own, use the length converter.
Who Uses an Area Calculator?
Homeowners use it for flooring, paint, turf and tiles. Builders and landscapers use it for quantities and quotes. Students use it to check geometry homework. For harder algebra that comes up with geometry, the quadratic calculator and the scientific calculator are good companions.
How to Use This Area Calculator
Choose a shape
Pick from rectangle, square, triangle, circle, trapezoid, parallelogram, ellipse or cube.
Enter the sizes
Type each measurement or drag the slider. The labels change with the shape.
Pick a unit
Choose from millimetres to miles. All sizes use the same unit.
Read the area
See the area, the working, a check, a diagram and the area in other units.