Cylinder Surface Area
Calculator

Total surface area is A = 2πr² + 2πrh, combining the two flat circular ends (2πr²) with the curved lateral surface that wraps around the side (2πrh). Together these account for every exposed surface of a solid cylinder.

If you 'unroll' the curved side of a cylinder flat, it becomes a rectangle with width equal to the circle's circumference (2πr) and height h, so its area is simply that rectangle's area, 2πrh. This unrolling trick is why a seemingly curved 3D surface reduces to simple rectangle math.

In that case, use only the 2πrh term and omit the 2πr² end-cap term, since an open pipe or tube has no flat circular faces to account for. Many practical cylinder problems, like paint needed for a pipe's exterior, only need this lateral term.

Since both terms in the formula scale with r (one as r², one linearly as r), doubling the radius more than doubles the surface area, though not by as extreme a factor as it does for volume. The exact effect depends on the ratio between the radius and height inputs.

Yes, an open-top cylinder only has one circular end plus the lateral surface, so its formula is A = πr² + 2πrh, missing one of the two πr² terms. Always check whether the real object has one, two, or zero flat circular faces before applying the full formula.