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Calculate the volume and capacity of tanks in gallons, liters, and cubic feet. Supports rectangular, cylindrical, oval, and capsule tank shapes.
V = L x W x H
Gallons = V (cu ft) x 7.48
V = Pi x r^2 x L
Where r = radius = diameter / 2
V = (Pi/4) x W x H x L
Approximation for elliptical cross-section
V = Cylinder + Sphere
Hemisphere ends combined as full sphere
| Tank Type | Typical Sizes | Common Uses |
|---|---|---|
| Water Heater | 40-80 gallons | Residential hot water |
| Propane Tank | 100-1000 gallons | Home heating, cooking |
| Septic Tank | 750-1500 gallons | Waste treatment |
| Rain Barrel | 50-100 gallons | Rainwater collection |
| Hot Tub | 200-500 gallons | Recreation |
| Swimming Pool | 10,000-30,000 gallons | Recreation |
There are approximately 7.48 US gallons in one cubic foot. Multiply cubic feet by 7.48 to get gallons.
For rectangular tanks, calculate total volume then multiply by the fill percentage. For cylindrical horizontal tanks, the calculation is more complex and depends on the fill height.
Water weighs 8.34 pounds per US gallon or about 1 kg per liter. A full 1,000-gallon tank weighs over 8,000 pounds.
Calculate your daily or peak usage, add 20% buffer, and select a tank size. Consider space constraints and weight capacity of the installation location.
Measure external dimensions and subtract wall thickness (typically 0.25-0.5 inches for plastic, more for steel). For cylinders, measure diameter across the widest point.
US gallon = 3.785 liters. Imperial gallon = 4.546 liters. This calculator uses US gallons, which are more common in North America.