Surface Area Calculator
Pick a solid, enter its dimensions, and get the surface area with a labeled diagram and the exact steps.
Runs entirely on your device - nothing is ever uploaded.
More tools
- Pythagorean Theorem Calculator Any missing side, with live diagram. Get started
- Volume Calculator Eight solids with diagrams and steps. Get started
- Half-Life Calculator Remaining amount after any elapsed time. Get started
- Radians to Degrees Converter Degrees, radians and turns, both ways. Get started
- Percent Error Calculator Experimental vs accepted, with steps. Get started
- Fractions Calculator Exact + − × ÷ with mixed numbers. Get started
- Abacus Interactive ten-rod soroban with live readout. Get started
- Grade Calculator Course average and letter grade. Get started
How to use the surface area calculator
- Pick one of the eight solids from the shape cards.
- Enter its dimensions in matching units.
- Read the surface area in square units, with the formula steps shown.
Which formula applies
Cube 6s², box 2(lw + lh + wh), sphere 4πr², cylinder 2πr(r + h), cone πr(r + s), square pyramid b² + 2bs with slant s, triangular prism (2 × Heron base area + perimeter × length), regular tetrahedron √3·a². For the space inside instead, flip to the volume calculator.
Surface area in the real world
Paint coverage, wrapping paper, and heat loss all run on surface area: a paint can's square-meter rating divides directly into a room's wall total. Bigger objects cool slower because volume grows faster than surface - the square-cube law behind elephant ears and laptop heat sinks. Compute the outside here; when you need capacity instead, the volume calculator takes the same eight shapes.