How to calculate surface area
Box: 2(LW+LH+WH) · Cylinder: 2πr(r+h) · Sphere: 4πr²
Worked example. Surface area: 94 square units.
Example inputs — Shape: Box; Length / radius: 5 units; Width (box only): 4 units; Height (box/cylinder): 3 units. Starting values are illustrative.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Total area of all outer surfaces. For a cylinder the first field is the radius; for a sphere only the radius is needed.
Assumptions & limitations
- Results are rounded for display.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
Is this the same as area?
Surface area is the total of every face of a 3D object; 'area' usually means one flat surface.