Area Calculator

Calculate area for rectangle, square, triangle, circle, ellipse, trapezoid, parallelogram, rhombus, kite, regular polygon, sector, and annulus.

Area Calculator helps you area of rectangles, triangles, circles, ellipses, trapezoids, polygons, sectors, rings, and more. Enter primary dimension, second dimension, and third dimension, review the breakdown, and use the guidance below to understand what the number means — and what it does not. What the Area calculator does Area Calculator is built for arithmetic, algebra, geometry, and number tools. Area of rectangles, triangles, circles, ellipses, trapezoids, polygons, sectors, rings, and more. You enter primary dimension, second dimension, and third dimension, then Simple Calculators computes the result instantly. Results use standard school and engineering formulas that run privately in your browser. How the math works Each shape uses its standard formula — base×height, πr², Heron’s formula for three sides, (a+b)h/2 for trapezoids, regular-polygon formulas, and sector/annulus formulas for circular pieces. The formula: Rectangle: A = width × length. Triangle: (base × height) ÷ 2. Circle: πr². Trapezoid: ((a + b) ÷ 2) × h. Switch shapes to see each formula worked out with your numbers.