Area calculator
Pick a shape, enter its measurements, and get the area with the formula and the result converted to other square units.
Area formulas
| Shape | Formula |
|---|---|
| Rectangle | A = l × w |
| Square | A = a² |
| Triangle | A = ½ × b × h |
| Circle | A = π r² |
| Trapezoid | A = ½ (a + b) h |
| Parallelogram | A = b × h |
| Ellipse | A = π a b |
| Circle sector | A = (θ / 360) π r² |
| Regular hexagon | A = (3√3 / 2) a² |
Why a triangle is half a rectangle
Draw the rectangle around any triangle using its base and height. The triangle’s apex splits that rectangle into two smaller rectangles, and the triangle takes exactly half of each. So its area is ½ × b × h, whatever the slant. A parallelogram is a rectangle with one end sliced off and moved to the other side, which is why its area is simply b × h.
Questions people ask
How do I find the area of an irregular shape?
Split it into rectangles, triangles and circle parts, calculate each area separately with this calculator, then add them (or subtract cut-outs). Floor plans are usually a few rectangles.
Why is the answer in square units?
Area counts how many unit squares cover a shape. A 3 m × 2 m rectangle is covered by 6 squares that are 1 m on each side, so the area is 6 m².
How do I convert square feet to square metres?
Multiply by 0.09290304 (that is 0.3048²). The result box above converts automatically; the area unit converter handles acres and hectares too.
What height do I use for a triangle or parallelogram?
The perpendicular height: the straight-line distance at 90° from the base to the opposite vertex or side, not the length of the slanted side.