Area Calculator

About the Area Calculator

An area calculator computes the surface area of any two-dimensional shape — rectangle, square, triangle, circle, trapezoid, parallelogram, ellipse, sector, regular polygon, or irregular quadrilateral — from its dimensions. Area calculations are essential for a huge range of practical tasks: calculating how much flooring, carpet, tile, or paint is needed for a room; determining the size of a garden bed; computing land area for real estate; sizing solar panels; calculating material requirements for sewing projects; and solving countless geometry problems in school and professional contexts. Our free area calculator handles all common 2D shapes with step-by-step formula display, and includes a combined area feature that lets you add multiple shapes together — useful for irregular rooms, L-shaped spaces, and combined plot areas. All results are shown in your chosen unit (square feet, square metres, square inches, square centimetres, acres, or hectares) with automatic unit conversion.

How It Works

Key area formulas: Rectangle: A = length x width. Example: 12 ft x 15 ft room = 180 sq ft. Square: A = side^2. Circle: A = pi x r^2. For a 10-foot diameter circle: A = pi x 5^2 = 78.54 sq ft. Triangle: A = 0.5 x base x height. Or using Heron's formula with three sides: A = sqrt(s(s-a)(s-b)(s-c)) where s = (a+b+c)/2. Trapezoid: A = 0.5 x (base1 + base2) x height. Parallelogram: A = base x height (perpendicular height, not slant side). Ellipse: A = pi x a x b (where a and b are the semi-major and semi-minor axes). Regular polygon with n sides of length s: A = (n x s^2) / (4 x tan(pi/n)). Sector (pie slice): A = 0.5 x r^2 x theta (theta in radians) or A = (angle/360) x pi x r^2.

Tips & Best Practices

• ✓Flooring purchase: always add 10% overage to your calculated area for rectangular rooms (for cuts and waste), 15% for diagonal installation, and 20% for herringbone or other complex patterns.
• ✓Paint coverage: 1 gallon typically covers 350-400 square feet. Calculate wall area as (perimeter x wall height) minus the area of all doors and windows.
• ✓Irregular room shapes: divide the room into simple rectangles, calculate each area, then add them together. For an L-shaped room, split it into two rectangles.
• ✓Land area: 1 acre = 43,560 square feet = 4,047 square metres = 0.405 hectares. 1 hectare = 10,000 square metres = 2.471 acres.
• ✓Circle versus square: a circle with the same perimeter as a square always has a larger area — circles are the most area-efficient shape for a given perimeter, which is why circular tanks and pipes maximise volume for a given material cost.
• ✓Area of composite shapes: the area calculator handles complex shapes by combination. An athletic track (two straight sections plus two semicircles) = rectangle area + circle area.
• ✓Surveying note: GPS-measured areas of land are typically calculated from coordinate polygons using the Shoelace (Gauss) formula — our irregular polygon area calculator uses this same method.
• ✓Unit confusion: be consistent with units throughout. If length is in metres and width in centimetres, convert one before calculating. The area calculator handles unit conversion automatically.

Who Uses This Calculator

Homeowners calculating flooring, carpet, tile, or paint quantities for renovation projects. Real estate professionals describing land and building areas for listings and appraisals. Landscape designers calculating garden bed, lawn, and hardscape areas for material ordering. Architects and engineers computing floor areas for building plans and energy calculations. Students solving geometry homework problems involving 2D shapes. Tailors and seamstresses calculating fabric requirements for garments. Farmers calculating field areas for planting, fertiliser, and irrigation planning. Solar panel installers computing available roof area for system sizing.