Area Calculator
Area of a circle, rectangle, triangle or trapezoid from its dimensions.
Enter values
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Step by step
The formula
circle: πr² · rectangle: l×w · triangle: ½bh · trapezoid: ½(a+b)h
All calculations run locally in your browser and update instantly as you type.
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Frequently asked questions
Which dimensions do I enter for each shape?+
Circle: A = radius. Rectangle: A = length, B = width. Triangle: A = base, B = height. Trapezoid: A and B = the two parallel sides, C = height. Unused fields are ignored.
What units does this use?+
Any unit you like — the area is in that unit squared. Enter metres to get m², feet to get ft², and so on.
All calculations run locally in your browser. Nothing you type is sent to a server.