Area, perimeter and volume of shapes
Pick a flat shape or a solid and enter its dimensions. The formulas are shown below the result.
Result
- Perimeter
- 20
- Diagonal
- 7.0710678
A = a²
P = 4a
d = a√2
Results use the same unit as the dimensions (area squared, volume cubed).
Key formulas
A circle’s area is πr² and its circumference 2πr. A trapezoid’s area is the average of the bases times the height: (a + b) · h / 2. A cylinder’s volume is base area times height, πr²h; a cone and a pyramid have a third of that: πr²h / 3 and a²h / 3. A sphere’s volume is 4/3 · πr³.
Perimeter of an ellipse
An ellipse’s perimeter has no simple exact formula. The tool uses Ramanujan’s approximation, which is accurate to a few parts per billion for ordinary ellipses.
Common questions
How do I get the volume in litres?
Enter dimensions in decimetres; the result in dm³ is litres. From centimetres, divide the cm³ result by 1000.
Where can I work out any triangle?
In the triangle calculator, which finds the area from sides and angles.