# Area Calculator

> Calculate area for rectangles, triangles, trapezoids, circles, sectors, ellipses, and parallelograms.

Page: https://askcalculators.com/calculator/area-calculator/
Definition: https://askcalculators.com/calculator/area-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/area-calculator/schema.json
Version: 2.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/area-calculator/?shape=rectangle&length=12&width=8

## Inputs
- shape: Shape; type=select; required; default=rectangle; values=rectangle|triangle|triangle-sides|trapezoid|circle|sector|ellipse|parallelogram
- length: Rectangle length; type=number; required; default=12; min=0.000001; showWhen=shape:rectangle
- width: Rectangle width; type=number; required; default=8; min=0.000001; showWhen=shape:rectangle
- base: Triangle base; type=number; required; default=10; min=0.000001; showWhen=shape:triangle
- height: Triangle height; type=number; required; default=6; min=0.000001; showWhen=shape:triangle
- triangleSideA: Triangle side a; type=number; required; default=3; min=0.000001; showWhen=shape:triangle-sides
- triangleSideB: Triangle side b; type=number; required; default=4; min=0.000001; showWhen=shape:triangle-sides
- triangleSideC: Triangle side c; type=number; required; default=5; min=0.000001; showWhen=shape:triangle-sides
- baseA: Trapezoid base 1; type=number; required; default=8; min=0.000001; showWhen=shape:trapezoid
- baseB: Trapezoid base 2; type=number; required; default=12; min=0.000001; showWhen=shape:trapezoid
- trapHeight: Trapezoid height; type=number; required; default=5; min=0.000001; showWhen=shape:trapezoid
- radius: Circle radius; type=number; required; default=5; min=0.000001; showWhen=shape:circle
- sectorRadius: Sector radius; type=number; required; default=5; min=0.000001; showWhen=shape:sector
- sectorAngle: Sector angle (degrees); type=number; required; default=90; min=0.000001; showWhen=shape:sector
- ellipseA: Ellipse semi-major axis; type=number; required; default=6; min=0.000001; showWhen=shape:ellipse
- ellipseB: Ellipse semi-minor axis; type=number; required; default=4; min=0.000001; showWhen=shape:ellipse
- parallelogramBase: Parallelogram base; type=number; required; default=10; min=0.000001; showWhen=shape:parallelogram
- parallelogramHeight: Parallelogram height; type=number; required; default=6; min=0.000001; showWhen=shape:parallelogram

## Outputs
- area: Area; format=number; primary
- perimeter: Perimeter or circumference; format=number
- shapeName: Shape; format=text

## Formula
Rectangle lw; triangle bh/2 or Heron; trapezoid (b₁+b₂)h/2; circle πr²; sector θπr²/360; ellipse πab; parallelogram bh.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.