Area Calculator
Calculate area of rectangles, circles, triangles, and more
About the Area Calculator
Finding the area of a shape means remembering the right formula, and there is a different one for every shape. This calculator collects seven of the most common — rectangle, square, circle, triangle, trapezoid, parallelogram, and ellipse — into one tool that picks the right formula and does the math once you choose a shape and enter its dimensions.
Students use it to check geometry homework; people planning real projects use it to size a room, a garden bed, or a piece of material. It returns not just the area but the perimeter (or circumference, for a circle) and shows the formula and steps, so the result is something you can learn from rather than just copy.
How to Use the Area Calculator
- Choose your shape from the dropdown (rectangle, square, circle, triangle, trapezoid, parallelogram, or ellipse).
- Enter the dimensions the chosen shape requires — the input fields change to match.
- Read the calculated area in square units.
- Check the perimeter or circumference and the formula breakdown shown with it.
Why Use ToolForge’s Area Calculator
- One tool covers seven shapes with the correct formula for each, so you do not need to look any of them up.
- Input fields adapt to the chosen shape, asking only for the dimensions that shape needs.
- It returns perimeter or circumference alongside area, and shows the formula and steps for learning and verification.
- Everything is computed locally and instantly with no account.
Frequently Asked Questions
Which shapes can this calculate?
Seven: rectangle (length × width), square (side²), circle (π × radius²), triangle (½ × base × height), trapezoid (½ × (base1 + base2) × height), parallelogram (base × height), and ellipse (π × semi-major × semi-minor). The required inputs change with your selection.
What units does the area come out in?
The area is in square units of whatever units you enter — if you input centimeters, the area is in square centimeters. The calculator does not assume a unit, so keep your inputs consistent and interpret the result in matching square units.
Does it also give the perimeter?
Yes. Along with the area, it reports the perimeter for straight-sided shapes and the circumference for a circle, so you get both measurements from a single calculation.
How do I find the area of a shape that isn't listed?
Break it into shapes that are. Most irregular outlines can be split into rectangles, triangles, and circle segments; calculate each piece here and add the areas together. Subtract pieces for cut-outs, such as a circular hole in a rectangular panel.
