Area, Perimeter & Volume Calculator
Calculate the area and perimeter of 2D shapes (circle, rectangle, triangle, trapezoid, ellipse, hexagon) and the volume and surface area of 3D solids (sphere, cylinder, cone, box, pyramid).
How to use
- 1Pick a shape.
- 2Enter its dimensions in any unit — results are in the same unit (squared or cubed).
How it's calculated
Circle: A = πr², C = 2πr. Sphere: V = 4⁄3πr³, S = 4πr². Cylinder: V = πr²h. Cone: V = ⅓πr²h. Ellipse perimeter uses Ramanujan's approximation.
Frequently asked questions
What units are the results in?
The same unit you enter, squared for area and cubed for volume — cm in, cm² and cm³ out.
How do I find the area from a circle's diameter?
Halve the diameter to get the radius first: a 10 cm diameter circle has r = 5 cm and area ≈ 78.54 cm².
How do I convert cubic feet to gallons?
1 ft³ ≈ 7.48 US gallons, and 1,000 cm³ = 1 litre.