Find the area of a rectangle, triangle, circle, trapezoid or parallelogram.
How the area calculator works
Pick a shape, enter its dimensions, and this calculator returns the area (and perimeter where it applies). It covers the shapes that come up most in school and around the house.
For floor space in square feet, see the square footage calculator.
A worked example
Take the starting scenario, a shape of Rectangle. That gives a area of 15. Alongside it, Perimeter comes out at 16. Change any field and every figure updates as you type.
Using the calculator
- Choose the shape.
- Enter its dimensions.
- Read the area.
The formula
rectangle = l×w · triangle = ½×b×h · circle = πr²
trapezoid = ½(a+b)h · parallelogram = b×h
Frequently asked questions
How do I find the area of a triangle?
Half the base times the height. For three sides, use the triangle calculator with Heron’s formula.
What’s the area of a circle?
Pi times the radius squared (πr²).
What units does it use?
Whatever units you enter — the result is in those square units. Keep dimensions consistent.