Question 1

How do I calculate surface area?

Accepted Answer

Pick a 3D shape from the sidebar, enter its measurements (use the same unit for every input), and the total surface area is shown instantly. The lateral (side) area is also shown separately, plus the formula and a labelled diagram.

Question 2

What is the difference between total and lateral surface area?

Accepted Answer

Total surface area includes every face of the solid, including the base(s). Lateral surface area excludes the base(s) — useful when you only need the side wall, for example when calculating paint or wrapping material for the sides of a cylinder or cone.

Question 3

What 3D shapes are supported?

Accepted Answer

Cube, rectangular prism (box), sphere, cylinder, cone, hemisphere, capsule (pill), square pyramid, frustum of a cone and torus. Each shape shows the exact formula used and the labelled diagram.

Question 4

Is this surface area calculator private?

Accepted Answer

Yes. All math runs in your browser with plain JavaScript. No inputs are sent to any server, no sign-up is required, and nothing is stored.