A cylinder 3 feet across and 4 feet tall holds 28.27 cubic feet — 211.5 US gallons, which weigh 1,765 pounds as water. The calculator above finds a cylinder's volume from its radius or diameter and height, with the area of its ends, its side and its whole surface.
How the calculator works
Choose whether you know the radius or the diameter, enter it and the height. The result is the volume in cubic feet, cubic yards, gallons, liters and cubic meters, the base, side and total surface, and the weight of water the cylinder holds.
The formula
Volume = π × r² × h. With the diameter, r = d ÷ 2 — using the diameter in place of the radius gives four times the volume, the most common mistake. The side is 2 π r h, each end π r².
| Cylinder | Cubic feet | Gallons |
|---|---|---|
| 1 ft across × 3 ft | 2.36 | 17.6 |
| 2 ft across × 4 ft | 12.57 | 94.0 |
| 3 ft across × 4 ft | 28.27 | 211.5 |
| 4 ft across × 6 ft | 75.40 | 564.0 |
Uses
Water tanks and barrels, concrete for round columns and Sonotube piers, sand in a round planter, the capacity of a well casing. For a lying tank partly full, use the tank volume calculator — a horizontal cylinder doesn't fill in proportion to its depth.
Common mistakes
- Diameter as radius. Halve it first.
- Outside dimensions. For capacity measure inside the walls.
- Inches cubed. Divide cubic inches by 231 for gallons, by 1,728 for cubic feet.
For other shapes, use the Volume Calculator; for a partly full tank, the Tank Volume Calculator.