VolLab

Surface Area Calculator

Every common solid's surface area, one dropdown away.

Side

Surface area

150

What you entered

Side: 5

1
Surface area = 6s²
6 × 5²= 150

Result

Surface area: 150

The total surface area is 150 square units — the sum of the area of every face of the solid.

Surface area of common solids

Each solid uses its own formula. All values are in square units of whatever unit you enter.

Solid	Dimensions	Surface area
Cone	r 3, h 4	75.3982
Box	5 x 4 x 3	94.0000
Cube	side 4	96.0000
Sphere	r 3	113.0973
Cylinder	r 3, h 6	169.6460

The sphere row at 113.0973 is the same number as its volume at radius 3, which is a genuine identity at that radius rather than a coincidence. A sphere has the smallest surface area of any shape enclosing a given volume, which is why droplets are spherical and why it is the most efficient shape for a pressure vessel. The cone figure includes its circular base as well as the curved surface; if you only want the curved part, subtract pi r squared.

Adding up every face

Surface area is the total area you'd need to cover a solid completely — for flat-faced shapes like a cube or box, that's literally summing each face's area; for curved shapes like a sphere or cylinder, calculus-derived formulas do the same job.

Why it's not just volume

Two solids can have identical volume but very different surface area (a flattened shape has far more surface for the same volume than a compact one) — this matters directly for heat loss, material/paint cost, and packaging design.

Frequently asked questions

How do I calculate surface area?

Cube: 6s². Sphere: 4πr². Cylinder: 2πr² + 2πrh. Cone: πr² + πrl (l = slant height). Box: 2(lw + lh + wh). Each formula adds up every face or uses a calculus-derived formula for curved surfaces.

Why does surface area matter?

Surface area determines: how much paint or wrapping you need, heat loss from a building or container, reaction rates in chemistry (more surface = faster reactions), and packaging material costs. It's the 'skin' of a 3D object.

Which shape has the smallest surface area for a given volume?

A sphere. It's the most efficient shape — minimum surface for maximum volume. That's why bubbles are spherical, and why spherical tanks minimize material cost. A cube of the same volume has about 24% more surface area.