Find the area of any common shape. This free area calculator covers rectangles, squares, circles, triangles, trapezoids, parallelograms and ellipses — just pick a shape and enter the dimensions.
Choose a shape and enter its dimensions. The area is given in square units of whatever unit you use (e.g. cm → cm²).
Area measures the 2-D space inside a shape. For perimeter of a circle use the circumference calculator; for 3-D space use the volume calculator.
How the Area Calculator Works
This tool finds the area of a shape you pick from a dropdown — rectangle, square, circle, triangle, trapezoid, parallelogram, or ellipse — using the dimension fields that appear for that specific shape. Each shape has its own formula, but all results come out in square units of whatever unit you enter.
Formula: Rectangle: Area = Width × Height. Square: Area = Side × Side. Circle: Area = π × Radius^2. Triangle: Area = 0.5 × Base × Height. Trapezoid: Area = 0.5 × (Side a + Side b) × Height, where a and b are the two parallel sides. Parallelogram: Area = Base × Height. Ellipse: Area = π × Semi-axis a × Semi-axis b.
- Shape — the dropdown selection that determines which dimension fields appear
- Width / Height — used for rectangle (also reused as Base/Height for triangle and parallelogram)
- Side — used for square (a single equal-sided edge length)
- Radius — used for circle
- Side a / Side b — the two parallel sides of a trapezoid, plus its Height
- Semi-axis a / Semi-axis b — the two half-axes of an ellipse
Example Scenarios
| Shape | Dimensions | Area |
|---|---|---|
| Rectangle | Width 5, Height 3 | 15 |
| Square | Side 4 | 16 |
| Circle | Radius 3 | 28.27 |
| Triangle | Base 6, Height 4 | 12 |
| Trapezoid | Side a 4, Side b 6, Height 5 | 25 |
| Ellipse | Semi-axis a 4, Semi-axis b 2 | 25.13 |
Area Calculator FAQ
Which shapes does this area calculator support?
It covers rectangles, squares, circles, triangles, trapezoids, parallelograms, and ellipses. Pick your shape from the dropdown and the relevant dimension fields appear automatically.How do I find the area of a trapezoid?
Select “Trapezoid” from the shape dropdown, then enter the two parallel sides (Side a and Side b) and the height between them. The calculator averages the two parallel sides and multiplies by the height.What units does the result use?
Whatever unit you enter for the dimensions is squared in the result, so entering measurements in centimeters gives an area in square centimeters (cm²), and inches gives square inches.How is an ellipse’s area calculated from two axes?
An ellipse uses its two semi-axes (half the length of its long and short diameters). The area is Ï€ multiplied by both semi-axis values, which reduces to the standard circle formula when both axes are equal.What’s the difference between area and circumference?
Area measures the flat space enclosed by a shape, while circumference (or perimeter) measures the distance around its edge. For circles specifically, use the circumference calculator to find the distance around instead.Can I calculate area for a parallelogram?
Yes, select “Parallelogram” from the dropdown and enter its base and height. The area is the base multiplied by the height, the same formula used for rectangles.Related Calculators
If your shape is a circle and you need the distance around it rather than the space inside, the circumference calculator handles that directly. Working in 3-D instead of 2-D? The volume calculator extends the same idea to boxes, spheres, and cylinders, and for a rectangle-only shortcut the rectangle area calculator is a simpler dedicated option.