Choose a Shape
Select a common two-dimensional shape and enter its dimensions.
Area Calculator
Calculate the area of common 2D shapes from their dimensions
How It Works
This calculator covers common shapes used in school, home projects, layouts, and quick geometry checks.
Outputs are unit-neutral: if dimensions are in feet, the result is square feet; if dimensions are in meters, the result is square meters.
- Rectangle area = length x width.
- Triangle area = base x height / 2.
- Circle area = pi x radius squared.
- Trapezoid area = (base 1 + base 2) x height / 2.
Formulas
Rectangle = length x width
Triangle = base x height / 2
Circle = pi x radius^2
Trapezoid = (base 1 + base 2) x height / 2
Room floor
12 ft x 15 ft rectangle
180 sq ft
Use matching units for both dimensions.
Round garden
8 ft radius circle
201.06 sq ft
Circle area uses radius, not diameter.
Triangle
10 m base and 6 m height
30 sq m
The height must be perpendicular to the base.
Should I enter a radius or diameter for a circle?
Enter the radius. If you know the diameter, divide it by two first.
What units does the result use?
The result is in squared versions of the dimension unit, such as square feet or square meters.
Can I calculate an irregular shape?
Break it into common shapes, calculate each area, and add or subtract the pieces.
Why does a triangle need height?
The perpendicular height determines the triangle’s base-to-top distance used by the area formula.