Area Calculator
Result
Calculate the area of rectangles, squares, triangles, circles, trapezoids, parallelograms and ellipses.
Formula
- Choose a shape and enter its relevant dimensions using the same length unit. The calculator applies the correct geometry formula for the selected shape and displays the area in square units.
- The main inputs are Shape, Side a (length / radius / base / semi-major axis), Side b (width / semi-minor axis / second parallel side), Height. Enter them in the units and format shown in the calculator.
- Keep comparable quantities in compatible units whenever the formula combines or compares them.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Area
- Shape: rectangle
- Side a (length / radius / base / semi-major axis): 8
- Side b (width / semi-minor axis / second parallel side): 5
- Height: 4
For a rectangle with a=8 and b=5, area=40 square units. For a circle with radius=8, area=64π≈201.06193 square units.
Sample result: Calculating…
Frequently asked questions
How is area calculated?
Select the shape and enter the required dimensions. Use the same length unit for all dimensions. The result is expressed in square units. What if an input is not used? That dimension is hidden and ignored.
What does the Area calculate?
Calculate the area of rectangles, squares, triangles, circles, trapezoids, parallelograms and ellipses.
Which values should I enter?
Enter Shape, Side a (length / radius / base / semi-major axis), Side b (width / semi-minor axis / second parallel side), Height using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Rectangle: A=a×b; Square: A=a²; Triangle: A=a×h/2; Circle: A=πa²; Trapezoid: A=(a+b)h/2; Parallelogram: A=a×h; Ellipse: A=πab..
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.