Free Area & Volume Calculator — 2D and 3D Shapes

How to use the area & volume calculator

Choose a shape. The input fields rebuild themselves for the shape you pick.
Enter the dimensions. Any positive numbers — decimals welcome.
Press Calculate. 2D shapes return area; 3D shapes return surface area and volume.
Read the formulas. Each result shows the exact substitution — perfect for showing your work.

Which shapes are supported?

2D shapes — rectangle, triangle, circle, trapezoid — give area. 3D shapes — cube, sphere, cylinder, cone — give both surface area and volume.

How is a cone's surface area calculated?

SA = πr² + πrl, where the slant height l = √(r² + h²). The tool shows the slant height and the substitution.

Why does the sphere's volume have 4/3 in it?

V = ⁴⁄₃πr³ — the 4/3 comes from integrating circular slices through the sphere. The tool just applies the formula and shows the substitution.

Can I enter fractions or decimals?

Yes — any positive number works, decimals included.

What is the difference between surface area and volume?

Surface area is the total skin of the shape, in square units; volume is the space inside it, in cubic units.

You’re here

Areas and surface/volume for common shapes.

This tool is free, with no account and no ads. If it saved you some time, consider supporting the indie dev behind it.