How it works
Calculate area for rectangles, triangles, trapezoids, circles, sectors, ellipses, and parallelograms. Inputs are calculated locally in the browser, and valid values are retained in the page URL for bookmarking.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
18-
?shape=ShapeChoice · Required · Default: rectangle · Accepted values: rectangle, triangle, triangle-sides, trapezoid, circle, sector, ellipse, parallelogram
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?length=Rectangle lengthNumber · Required · Default: 12 · Used when shape = rectangle
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?width=Rectangle widthNumber · Required · Default: 8 · Used when shape = rectangle
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?base=Triangle baseNumber · Required · Default: 10 · Used when shape = triangle
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?height=Triangle heightNumber · Required · Default: 6 · Used when shape = triangle
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?triangleSideA=Triangle side aNumber · Required · Default: 3 · Used when shape = triangle-sides
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?triangleSideB=Triangle side bNumber · Required · Default: 4 · Used when shape = triangle-sides
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?triangleSideC=Triangle side cNumber · Required · Default: 5 · Used when shape = triangle-sides
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?baseA=Trapezoid base 1Number · Required · Default: 8 · Used when shape = trapezoid
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?baseB=Trapezoid base 2Number · Required · Default: 12 · Used when shape = trapezoid
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?trapHeight=Trapezoid heightNumber · Required · Default: 5 · Used when shape = trapezoid
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?radius=Circle radiusNumber · Required · Default: 5 · Used when shape = circle
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?sectorRadius=Sector radiusNumber · Required · Default: 5 · Used when shape = sector
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?sectorAngle=Sector angle (degrees)Number · Required · Default: 90 · Used when shape = sector
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?ellipseA=Ellipse semi-major axisNumber · Required · Default: 6 · Used when shape = ellipse
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?ellipseB=Ellipse semi-minor axisNumber · Required · Default: 4 · Used when shape = ellipse
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?parallelogramBase=Parallelogram baseNumber · Required · Default: 10 · Used when shape = parallelogram
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?parallelogramHeight=Parallelogram heightNumber · Required · Default: 6 · Used when shape = parallelogram
Outputs
3-
areaAreaNumber · Primary output
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perimeterPerimeter or circumferenceNumber
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shapeNameShapeText
Formula notes
Rectangle lw; triangle bh/2 or Heron; trapezoid (b₁+b₂)h/2; circle πr²; sector θπr²/360; ellipse πab; parallelogram bh.
Input guidance
Use consistent units for every length or measurement in the same calculation. Results are educational mathematical estimates and should be checked before high-stakes use.