Area Calculator
Calculate area for rectangles, triangles, and circles.
Amortization schedule
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Showing first 12 of months.
Growth over time
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Introduction
Area Calculator — Calculate area for rectangles, triangles, and circles. Enter Shape, A (length / base / radius), B (width / height) to get an instant, accurate result.
Formula
Rectangle: area = a×b. Triangle: area = ½×a×b (base × height). Circle: area = π×a² (a as radius).
Step-by-step
- Enter the Shape.
- Enter the A (length / base / radius).
- Enter the B (width / height).
- Click Calculate to see your result instantly.
Real-world example
Example: With Shape = rectangle, A (length / base / radius) = 4, B (width / height) = 5, the Area Calculator gives Area: 20.
Frequently Asked Questions
Which shapes are supported?
Rectangle, triangle, and circle.
For a triangle, what do a and b represent?
Base and height, not two arbitrary sides.
What inputs does the Area Calculator need?
You'll need to provide: Shape, A (length / base / radius), B (width / height). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Area Calculator?
The Area Calculator applies the formula exactly as calculated — Rectangle: area = a×b. Triangle: area = ½×a×b (base × height). Circle: area = π×a² (a as radius). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Area Calculator free to use?
Yes, the Area Calculator is completely free, requires no signup, and runs instantly in your browser.
About the Area Calculator
The Area Calculator uses a real, verifiable formula — Rectangle: area = a×b. Triangle: area = ½×a×b (base × height). Circle: area = π×a² (a as radius). — so results are accurate every time, not an approximation.