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Area calculator (square, circle, triangle...)

Calculate the area of a square, rectangle, triangle, circle and trapezoid in seconds.

Used in rectangle and trapezoid

Used in triangle and trapezoid

Area
78.5398 u²
Formula usedπ × A²

Use the same unit for all measures; the result is in squared units (u²).

How the calculation works

Areas of the main plane figures:

  • Square: side²
  • Rectangle: base × height
  • Triangle: (base × height) ÷ 2
  • Circle: π × radius²
  • Trapezoid: ((major base + minor base) ÷ 2) × height

Frequently asked questions

How to find the area of a circle?

Multiply π (≈ 3.1416) by the radius squared. The radius is half the diameter.

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Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources