Area calculator for shapes
Pick a shape and type its measurements, all in the same unit. The area is given in that unit squared.
Result
12 m²Area
- Perimeter
- 14 m
Inputs
- Shape
- Rectangle
- Length
- 4
- Width
- 3
- Unit of the measurements
- m
How it is calculated
Rectangle: length × width. Triangle: base × height ÷ 2. Trapezoid: (B + b) ÷ 2 × h.
Result
Area
- Perimeter
- 14 m
How it is calculated
- Rectangle: length × width. Triangle: base × height ÷ 2. Trapezoid: (B + b) ÷ 2 × h.
- Triangle from 3 sides: Heron’s formula.
- Circle: π × r². Ellipse: π × a × b. Sector: π × r² × angle ÷ 360.
- Regular polygon: n × s² ÷ (4 × tan(π ÷ n)).
Example
A 4 m by 3 m rectangle has an area of 12 m² and a perimeter of 14 m.
Good to know
- All measurements must use the same unit.
- A triangle with one side longer than the other two together is impossible: the tool says so.
- The ellipse perimeter is an approximation (Ramanujan), very accurate.
Frequently asked questions
What is this tool used for?
Pick a shape and type its measurements, all in the same unit. The area is given in that unit squared.
How is the result calculated?
Rectangle: length × width. Triangle: base × height ÷ 2. Trapezoid: (B + b) ÷ 2 × h.
What should I check before using the result?
All measurements must use the same unit.