Calculate the surface area of common 3D shapes — cube, box, sphere, cylinder, and cone — with clear formulas and diagrams.
Pick the 3D shape you need at the top of the calculator — Cube, Box, Sphere, Cylinder, or Cone. The input fields will automatically switch to match the measurements that shape requires. Enter your dimensions using any consistent unit (inches, cm, meters — just keep every field in the same unit) and press "Calculate Surface Area" to get the total outer surface area of the solid.
Cube: SA = 6s², where s is the length of one side.
Rectangular Box: SA = 2(lw + lh + wh), where l, w, and h are length, width, and height.
Sphere: SA = 4πr², where r is the radius.
Cylinder: SA = 2πr² + 2πrh = 2πr(r + h), combining the two circular ends with the curved side.
Cone: SA = πr² + πrl, where l is the slant height, calculated automatically as l = √(r² + h²) from the radius and vertical height you enter.
Say you want the surface area of a cylinder with radius 4 cm and height 10 cm. First find the two circular ends: 2πr² = 2 × π × 4² ≈ 100.53 cm². Then find the curved side: 2πrh = 2 × π × 4 × 10 ≈ 251.33 cm². Adding them gives a total surface area of approximately 351.86 cm² — exactly what this calculator returns instantly when you enter r = 4 and h = 10.
Surface area calculations come up constantly in real life — figuring out how much paint covers a cylindrical tank, how much wrapping paper covers a box, how much material coats a dome, or how much fabric is needed for a cone-shaped lampshade. Because the tool separates each shape into its own clearly labeled fields, there's no need to remember which variable is which — just look at the diagram, match the letters, and calculate.
Does it matter which unit I use? No — the formulas work the same regardless of unit, so the result will simply be in that unit squared (e.g. cm² if you entered cm).
What's the difference between surface area and volume? Surface area measures the total area of the outer "skin" of a shape, while volume measures the space it occupies inside. Our Volume Calculator covers the latter for these same shapes.
Commonly cubes, spheres, cylinders, cones, and prisms.
The total area covering the outside of a 3D object.
Surface area measures the 2D skin; volume measures the 3D space contained within.