Calculating the volume of water in a vessel is essential for architects, engineers, and pool owners alike. The required formula depends on the vessel’s shape—rectangular or circular being the most common in everyday use.
Rectangular Vessels: For any prism‑shaped container, the volume is simply the product of its length, width, and depth.
V = L × W × D
where L is length, W width, and D depth. For example, a swimming pool that measures 10 ft long, 12 ft wide, and 6 ft deep holds:
V = 10 ft × 12 ft × 6 ft = 720 ft³
Since 1 ft³ equals 7.48 gal, the pool contains roughly 5,386 gal of water.
When the container is a right circular cylinder, the volume is found with the radius (r), depth (D), and the constant π (≈ 3.14).
V = π r² D
Take a round pool 20 ft in diameter and 6 ft deep. The radius is 10 ft.
V = 3.14 × (10 ft)² × 6 ft ≈ 1,884 ft³
Converted to gallons: 1,884 ft³ × 7.48 gal/ft³ ≈ 14,092 gal.
For irregular shapes, more advanced methods—such as integration or CAD modeling—are recommended.
Source: biDaala studio/Shutterstock
