Area Calculator
Calculate the area of any flat shape instantly — square, rectangle, triangle, circle and more. Free calculator with the formula shown, no signup needed.
About this tool
Area measures the size of a flat surface - the floor of a room, a lawn to seed, a wall to paint, or a plot of land. Getting it right saves money: too little paint means a second trip, too much means waste.
Select your shape, enter its dimensions, and this area calculator returns the exact area instantly.
How to use
Choose square, rectangle, triangle, or circle. Fill in only the dimensions that apply - a circle needs just the radius, a triangle needs base and height.
Press Calculate Area and the answer appears in square units of your measurements.
The math behind it
Square: side^2. Rectangle: length x width. Triangle: (base x height) / 2. Circle: pi x r^2.
For rooms with alcoves or odd corners, split the floor plan into rectangles and triangles, calculate each, and add them up.
Frequently asked questions
How do I measure the area of a room for flooring?
What is the difference between area and perimeter?
How many square feet are in a square meter?
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