Surface Area Calculator

Use this free online surface area calculator to find the total surface area of a cube, rectangular box, sphere, cylinder, or cone. Pick your shape, enter its dimensions, and get an accurate surface area result instantly.

How to Use the Surface Area Calculator

  1. Select your "Shape" - cube, rectangular box, sphere, cylinder, or cone.
  2. Enter the required dimensions for that shape (e.g. Side for a cube, Length/Width/Height for a box, Radius for a sphere, or Radius and Height for a cylinder or cone).
  3. Click "Calculate" to compute the surface area.
  4. Review the "Surface Area" result shown below the button.

Frequently Asked Questions

Cube uses 6 × side², rectangular box uses 2 × (length×width + length×height + width×height), sphere uses 4 × π × radius², cylinder uses 2πr² + 2πrh, and cone uses πr² + πr × slant height, where slant height = √(radius² + height²).

All dimensions must be positive numbers greater than zero. Entering zero, a negative value, or leaving a required field blank produces a shape-specific error message instead of a result.

For a cylinder with radius = 3 and height = 5, the surface area is 2π(3²) + 2π(3)(5) = 2π(9) + 2π(15) ≈ 56.549 + 94.248 ≈ 150.796 square units.

The cone's slant height is calculated as √(radius² + height²) using the Pythagorean theorem, then used in the lateral surface area term π r × slant height, which is added to the base area π r² for the total surface area.
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