Surface Area Calculator

Surface Area – Quick Cheat Sheet

Cube: SA = 6a²
Rectangular Prism: SA = 2(lw + lh + wh)
Sphere: SA = 4πr²
Cylinder (right circular): SA_total = 2πrh + 2πr² and SA_lateral = 2πrh
Cone (right circular): s = √(r² + h²), SA_total = πrs + πr², SA_lateral = πrs
Triangular Prism: SA = (perimeter of base)·L + 2·(area of base)
Units: If your dimensions are in cm, area is in cm² (same for m², in², ft², etc.).
Inputs must be non-negative. Use consistent units for all dimensions.

Tips & notes

“Lateral area” excludes base(s). “Total area” includes base(s).
For a triangular prism with arbitrary base, provide two other sides (s1, s2) plus base b and its height h to compute perimeter and base area.
π is taken from PHP’s M_PI for precision.