Method
Each shape uses its standard Euclidean formula, with sector angles converted to a fraction of a full turn and regular polygons decomposed into congruent triangles.
Math worksheet
Area Calculator
Calculate area for rectangles, triangles, circles, ellipses, trapezoids, sectors and regular polygons with formula-level detail.
The calculation runs locally. Exact-integer tools avoid floating point; decimal and transcendental tools report rounding limits.
Method and verification guide
How the Area Calculator works
Each shape uses its standard Euclidean formula, with sector angles converted to a fraction of a full turn and regular polygons decomposed into congruent triangles. The calculator keeps the intermediate values visible so you can reproduce the answer independently.
Interpret the result
Area is expressed in square units; scaling all lengths by k scales area by k².
Check the assumptions
Curved and regular-polygon results assume exact ideal geometry and a common input unit.
Local calculation
Everything runs in this browser. Inputs are not sent to an external calculator.
Rounding
Displayed values may be rounded for readability while calculations use full floating-point precision unless the tool explicitly uses exact integers.
Scope
Curved and regular-polygon results assume exact ideal geometry and a common input unit.
Simple by design
Three steps to a clearer number.
Enter your details
Use realistic values in each field. You can change them anytime.
Calculate instantly
The formula runs locally, so there is no account or waiting time.
Use the result
Treat the answer as a practical estimate for your next decision.