Area Calculator
Calculate the area of rectangles, circles, triangles, trapezoids and more shapes.
Enter your values to see the result.
Continue your work
- Volume Calculator — Calculate volumes of 3D shapes.
- Square Feet Calculator — Measure rooms in square feet.
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Clear instructions
Find steps, examples and limitations below.
Use online
Open the tool in a supported web browser.
Free to use
No sign-up required. Tool-specific limits may apply.
How to use the Area Calculator
Calculate the area of rectangles, circles, triangles, trapezoids and more shapes.
- 1 Choose the shape and unit.
- 2 Enter the measurements shown for that shape.
- 3 Read the area, perimeter and the area in other units.
Example and practical tips
A 3-4-5 triangle entered with three sides has an area of 6 square units, calculated with Heron’s formula.
Frequently asked questions
What is Heron’s formula?
It finds a triangle’s area from its three sides: √(s(s − a)(s − b)(s − c)), where s is half the perimeter.
Why are the units squared?
Area is measured in square units, such as m² or ft².
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