Calculate the area of any 2D shape. Choose a shape, enter its dimensions, and get the area and perimeter instantly. Supports rectangle, square, circle, triangle, trapezoid, ellipse, and more.
| Shape | Area |
|---|---|
| Rectangle | length × width |
| Square | side² |
| Triangle | (base × height) ÷ 2 |
| Circle | π × radius² |
| Trapezoid | ((a + b) ÷ 2) × height |
| Parallelogram | base × height |
| Ellipse | π × a × b |
For triangles and parallelograms, height is the perpendicular distance from the base to the opposite vertex or side — not the length of a slanted edge. Using the slanted side overstates the area, often substantially on a steeply angled shape.
The circle formula takes the radius. Measuring across a circle gives the diameter, which must be halved first. Substituting diameter directly gives four times the true area, since the term is squared.
Break them into rectangles and triangles, calculate each, then add. For a shape with a bite taken out, calculate the full outline and subtract the missing piece.
This decomposition handles almost any real-world floor plan, garden or site.
Area units are squared, and they do not scale the way lengths do. There are 12 inches in a foot but 144 square inches in a square foot, and 3 feet in a yard but 9 square feet in a square yard.
Convert all measurements to the same unit before calculating, not afterwards. Converting an area by the linear factor is one of the most common and most costly measurement errors.