Area calculator
Area and perimeter of rectangles, triangles, circles, trapezoids and polygons.
How it is calculated
Rectangle: L × W. Triangle: ½ × base × height. Circle: π × r². Trapezoid: ½ × (a + b) × h. Polygon from coordinates: shoelace formula, ½ × |Σ(xᵢ × yᵢ₊₁ − xᵢ₊₁ × yᵢ)|.
How to use the Area Calculator
Calculate the area and perimeter of rectangles, triangles, circles, trapezoids and any polygon from its corner coordinates, in square metres and square feet.
- Choose the shape.
- Enter its dimensions, or the corner coordinates of a polygon in order around the shape.
- Read the area and perimeter in both metric and imperial units.
Worked example
A 6 m × 4 m room is 24 m², or about 258.3 ft², with a perimeter of 20 m. A circle with a 2 m radius is 12.57 m². An L-shaped plot can be entered as a polygon from its corner coordinates.
Good to know
- For irregular plots, take coordinates from the survey drawing and enter them in order, clockwise or anticlockwise.
- 1 m² is 10.764 ft², and 1 ft² is 0.0929 m².
- For several rooms, the Room Area Calculator adds them up with a built-up area estimate.
Questions
How do I find the area of an irregular shape?
Choose Polygon and enter the corner coordinates in order around the shape, one corner per line.
Is anything I enter saved or sent?
No. The calculation runs in your browser. Nothing you type is sent anywhere. You can copy the result, print it or download it as a CSV.