Area Calculator
Choose a shape and enter its dimensions to get the area and perimeter.
Results
- Area (square units)
- Perimeter (units)
The result is in the square of the unit you entered: metres give m², feet give ft².
How much flooring does a room need, how much seed for a lawn, how much paint for a wall? It all starts with getting the area right.
The calculator supports eight shapes. For a triangle there are two routes: base and height if you know them, or Heron’s formula from the three sides.
How to calculate Area
- Choose the shape.
- Enter the dimensions, all in the same unit.
- Read the area and, where available, the perimeter; the result is in the square of the unit you used.
Area formula
Rectangle: length × widthCircle: π × r²Triangle: base × height ÷ 2Trapezoid: (base a + base b) × height ÷ 2
Area example
A room 5 m by 3 m is 15 m² with a perimeter of 16 m. A circular pool with a 5 m radius covers π × 5² = 78.54 m².
Area: common questions
How do I calculate square footage?
Multiply the length by the width, both in feet. For an L-shaped room, split it into rectangles and add their areas.
How do I find the area of a circle from its diameter?
Halve the diameter to get the radius, then apply π × r².
How is a triangle’s area found from three sides?
With Heron’s formula: area = √(s(s−a)(s−b)(s−c)), where s is half the perimeter. If the sides cannot form a triangle there is no result.