Area Calculator
Find the area of circles, triangles, rectangles and more shapes.
How to use this tool
- Pick a shape.
- Enter the required dimensions.
- See the area with the formula used.
How it works
Each shape applies its formula: square = s²; rectangle = l x w; triangle = 0.5bh; circle = pi r²; trapezoid = (a+b)/2 x h; parallelogram = b x h; ellipse = pi abc.
Tips
- Break irregular rooms into rectangles and triangles, then add.
- Consistent units matter — mixing feet and inches needs conversion first.
Limitations
Assumes simple planar shapes; curves and irregular perimeters need decomposition.
Frequently asked questions
How is the area of a circle found?
A = pi x r squared. Radius in, area out, in any unit system.
How about a triangle?
A = 0.5 x base x height. For three-side inputs, the tool can also use Heron's formula.
Can I use feet and metrics?
Enter any unit for the side; the result is in the same unit squared.