Surface Area Calculator

1. Select a shape from the buttons: Cube, Rectangular Prism, Sphere, Cylinder, Cone, or Triangular Prism.
2. Enter the dimensions for that shape. Each shape shows only the fields it needs.
3. Read the results. Total surface area includes all faces. Lateral surface area excludes the base(s) and top(s). The formula used is shown with your actual numbers substituted in.

All units are consistent: if you enter centimeters, the area is in square centimeters.

Cube (side a):
  Total SA     = 6a²
  Lateral SA   = 4a²

Rectangular Prism (l, w, h):
  Total SA     = 2(lw + lh + wh)
  Lateral SA   = 2(l + w)h

Sphere (radius r):
  Total SA     = 4πr²  (no separate lateral)

Cylinder (radius r, height h):
  Total SA     = 2πr(r + h)
  Lateral SA   = 2πrh
  Base area    = πr²

Cone (radius r, height h, slant l = √(r²+h²)):
  Total SA     = πr(r + l)
  Lateral SA   = πrl
  Base area    = πr²

Triangular Prism (triangle sides a, b, c; prism length l):
  Triangle area (Heron's formula): s = (a+b+c)/2, A = √[s(s-a)(s-b)(s-c)]
  Total SA     = (a + b + c)l + 2A
  Lateral SA   = (a + b + c)l