Geometry 9 min read

Area Formulas Cheat Sheet for All 2D Shapes (With Examples)

A complete reference cheat sheet for calculating the area of 2D geometric shapes: squares, rectangles, triangles, circles, parallelograms, trapezoids, and ellipses.

Table of Contents

What Is Area?

Area measures the total amount of two-dimensional space enclosed inside the boundary of a flat shape. It is always expressed in square units (e.g., cm², m², sq ft).

Essential 2D Area Formulas

  • Square: Area = side² = a²
  • Rectangle: Area = width × height = w · h
  • Triangle: Area = ½ × base × height = ½ · b · h
  • Circle: Area = π × radius² = π · r²
  • Parallelogram: Area = base × height = b · h
  • Trapezoid: Area = ½ × (base₁ + base₂) × height
  • Ellipse: Area = π × semi-major axis (a) × semi-minor axis (b)
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Reviewed by Applied Math Specialists • Editorial Policy
Updated: August 11, 2026

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