Outer faces and curved surfaces
Cylinder Surface Area Calculator
Enter the radius or diameter and the height. Choose how many circular ends to include, and see the curved surface area separately.
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Cylinder surface area formula
The curved side, or lateral area, is 2πrh. Each flat circular end has area πr². The total for a closed cylinder is 2πrh + 2πr².
If you have diameter d, use r = d ÷ 2. With one end open, include one circular end: A = 2πrh + πr². With both ends open, A = 2πrh.
Example: radius 3 ft, height 5 ft
The curved surface is 2 × π × 3 × 5 = 30π ≈ 94.25 ft². Two ends add 18π ≈ 56.55 ft². The closed cylinder total is 48π ≈ 150.80 ft².
Why the side becomes a rectangle
Unroll the curved side of a right circular cylinder and it becomes a rectangle with width 2πr and height h. Multiplying these dimensions gives its lateral area.
An opening has no face to include. For a pipe, this calculation covers the chosen cylindrical side and ideal end discs; it does not calculate the annular rim, inside wall or wall thickness of a hollow tube.
For the space inside, use the cylinder volume calculator.
Enter every length in the same unit. Results are rounded for display; calculations use unrounded values and the full precision of π.