📐 Math & Geometry

Area Calculator

Use this free area calculator to calculate the area of rectangles, circles, triangles and other common shapes. Select a shape and unit, enter the relevant dimensions, and compare the result in m², ft², cm² and in².

8 shapes
All common forms
4 units
m² · ft² · cm² · in²
Private
Runs in your browser
📐
Area Calculator

Pick a shape, enter your measurements, and choose your preferred unit. Results convert automatically to all common area units.

⚠️ Please fill in all required fields with positive numbers.
Area
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Square metres
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Square feet
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Square cm
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Square inches
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Area Formulas for Every Common Shape

Area is the amount of two-dimensional space enclosed by a shape, measured in square units (m², ft², cm², etc.). Different shapes require different formulas — this calculator handles eight of the most common, including rectangles, circles, triangles, trapezoids, ellipses, parallelograms, sectors, and squares.

Rectangle: A = length × width Square: A = side² Circle: A = π × radius² Triangle: A = ½ × base × height Trapezoid: A = ½ × (base1 + base2) × height Ellipse: A = π × semi-major × semi-minor Parallelogram: A = base × height Sector: A = ½ × radius² × angle(rad) = (θ/360) × π × r²

Practical Uses: When Do You Need to Calculate Area?

  • Flooring and tiling: Calculate the area of a room to estimate how many tiles, planks, or rolls of carpet you need. Always add 10–15% for cuts and waste.
  • Painting: Estimate wall area (length × height per wall, minus doors and windows) to calculate how many litres of paint you need.
  • Gardening and landscaping: Calculate the area of a lawn, garden bed, or paved area to estimate materials like topsoil, mulch, or paving.
  • Construction: Calculate the area of a slab, roof section, or wall panel for material and cost estimates.
  • Fabric and crafts: Calculate the area of material needed for clothing patterns, quilts, or upholstery projects.
  • Real estate: Calculate the floor area of a property, or the area of a block of land.
  • Maths and school: Geometry problems involving area are common in school maths — use this calculator to check your work.
💡 Flooring tip: For a rectangular room, measure length and width in metres, multiply them, then add 10% for waste. For irregular rooms, break them into rectangles and add the areas together. Use the calculator multiple times and add the results.

Area Unit Conversions — Quick Reference

FromTo square metresTo square feetTo square cmTo square inches
1 m²110.763910,0001,550.0
1 ft²0.09291929.03144
1 cm²0.00010.00107610.155
1 in²0.0006450.0069446.4521
1 yd²0.83698,3611,296

How to Measure an Irregular Room for Flooring

Most rooms aren't perfectly rectangular — they have alcoves, bay windows, or L-shapes. The standard approach is to divide the room into rectangles (and sometimes triangles), measure each section, calculate its area, and add them together.

  1. Sketch the room from above and divide it into rectangles.
  2. Measure the length and width of each rectangle.
  3. Use this calculator's rectangle mode to find each area.
  4. Add all the areas together.
  5. Add 10–15% for cuts and waste.

For more on flooring material estimation, This Old House has a detailed guide with worked examples for different room shapes.

Circle Area vs. Circumference — What's the Difference?

The area of a circle (π × r²) measures the space inside the circle — useful for calculating material covering a circular surface. The circumference (2π × r) measures the distance around the outside — useful for fencing or borders. This calculator gives area only — circumference is a separate measurement (2π × r).

Frequently Asked Questions

How do I calculate the area of a rectangle?
Area = length × width. For a room that is 5m × 4m, the area is 20 m². Enter the dimensions in the rectangle mode above for an instant result in your chosen unit.
How do I calculate the area of a circle?
Area = π × radius². If you know the diameter, the radius is diameter ÷ 2. A circle with radius 5m has an area of π × 25 ≈ 78.54 m². Enter the radius in circle mode above.
How do I calculate the area of a triangle?
Area = ½ × base × height (perpendicular height). For a triangle with a base of 6m and height of 4m, the area is ½ × 6 × 4 = 12 m². Enter base and height in triangle mode above.
How do I convert square metres to square feet?
Multiply by 10.7639. So 20 m² = 215.28 ft². The calculator shows all four unit conversions simultaneously after you calculate.
How do I calculate area for flooring or tiling?
Measure length and width of each rectangular section, calculate each area using rectangle mode, sum them, then add 10–15% for cuts and waste. For L-shaped rooms, split into two rectangles and add the areas.
What is the area of a trapezoid?
Area = ½ × (base1 + base2) × height, where base1 and base2 are the parallel sides. Enter these three values in trapezoid mode above.
How do I calculate the area of an irregular shape?
Break the irregular shape into rectangles, triangles, or circles. Calculate each section separately using the relevant mode, then add the areas together.
Is my data private?
Yes — this calculator runs entirely in your browser. Nothing is uploaded or stored. It works instantly and privately, and functions offline once the page has loaded.
Quick conversions
1 m²10.764 ft²
1 ft²0.0929 m²
1 m²10,000 cm²
1 acre4,047 m²
1 hectare10,000 m²
1 km²1,000,000 m²
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