Area Calculator
Calculate the area of a rectangle, triangle, circle, trapezoid, ellipse, sector or regular polygon — in any unit, with the perimeter and conversions.
Area formulas
| Shape | Area |
|---|---|
| Square | A = a² |
| Rectangle | A = a × b |
| Triangle | A = b × h ÷ 2 |
| Circle | A = π r² |
| Ellipse | A = π a b |
| Trapezoid | A = (a + b) ÷ 2 × h |
| Parallelogram | A = b × h |
| Circular sector | A = π r² × θ ÷ 360° |
| Regular polygon | A = n a² ÷ (4 tan(180° ÷ n)) |
Examples
A rectangle of 5 × 3 in has an area of 15 in². A circle with a radius of 3 cm has an area of π × 9 ≈ 28.27 cm². A trapezoid with parallel sides 5 and 3 and a height of 4 has an area of (5 + 3) ÷ 2 × 4 = 16.
Units
Choose the unit of your measurements; the area comes out in the same unit squared, with conversions to square metres and square feet — and to hectares and acres for large areas. Remember that 1 m² is 10,000 cm², not 100, because both sides are converted.
Frequently asked questions
How do I calculate the area of a rectangle?
Multiply the length by the width: 5 × 3 = 15 square units.
How do I find the area of a triangle?
Multiply the base by the height and divide by 2. If you only know the three sides, use the triangle calculator (Heron’s formula).
How many square feet are in a square metre?
About 10.764 ft². One square foot is 0.0929 m².