Surface Area Calculator
Enter dimensions in the linear unit for m² (e.g. meters).
| Unit | Surface area |
|---|---|
| m² | 24 |
| cm² | 240000 |
| ft² | 258.33385 |
| in² | 37200.0744 |
SA = 6s²
Surface Area Formulas
Surface area is the total area of all outer faces of a three-dimensional object. For shapes with curved surfaces, the formula integrates around the geometry; for polyhedra, sum the areas of each flat face.
A cube with edge s has SA = 6s² — six identical square faces. A rectangular box has SA = 2(lw + lh + wh), with lateral SA = 2h(l+w) when the top and bottom are excluded. A sphere has SA = 4πr², remarkably equal to four great-circle areas.
A cylinder has total SA = 2πr² + 2πrh (two circular caps plus the curved side). The lateral (side only) SA = 2πrh. A cone has total SA = πr² + πr√(r²+h²), where the slant height is √(r²+h²). A square-base pyramid adds the four triangular faces to the base area.
A hemisphere includes the curved dome plus the flat circular base: SA = 3πr². A torus has SA = 4π²Rr. Where both total and lateral values apply, this calculator shows both.
Select your shape, enter dimensions, and use the schematic diagram as a visual reference. Surface area is essential for heat transfer, paint coverage, material wrapping, and biology (cell membrane estimates).
Examples
| Example | Result |
|---|---|
| Cube s=3 | SA = 54 |
| Sphere r=2 | SA ≈ 50.27 |
| Cylinder r=2, h=5 | Total ≈ 87.96 |
| Hemisphere r=3 | SA ≈ 84.82 |
Frequently asked questions
It excludes the top and bottom (or base) faces — only the curved or side surfaces.
s = √(r² + h²), used in the lateral surface πrs.
Yes. SA = 4π²Rr for a standard torus.