Enter your Tank Shape and dimensions — Length, Width, Height for rectangular or Diameter for cylindrical — along with Fill Height, and the Water Tank Size Calculator gives you Total Volume, current Filled Volume, and Remaining Capacity in your chosen units.
Total Tank Volume
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Filled Volume
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Remaining Capacity
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Tank volume depends on the shape. For rectangular tanks, multiply length × width × height. For cylindrical tanks, use π × radius² × height. Our calculator handles all common tank shapes automatically.
Vertical cylinders are simpler - just multiply the circular base area by height. Horizontal cylinders require more complex calculations, especially for partial fill volumes, as the water forms a segment shape.
Our calculations assume perfect geometric shapes. Real tanks may have wall thickness, fittings, or irregular shapes that slightly reduce actual capacity. These calculations provide reliable estimates for planning purposes.
Yes, enter a fill height value to calculate how much water is currently in the tank and remaining capacity. This is useful for monitoring water levels and planning refills.
You can input dimensions in feet, inches, meters, or centimeters. Results can be displayed in US gallons, liters, cubic feet, or cubic meters to match your preferred measurement system.
Cylindrical tanks distribute pressure more evenly, are stronger structurally, and use materials more efficiently. They're also easier to clean and have fewer corners where sediment can accumulate.
Consider your daily water usage, backup requirements, and local regulations. Typical homes need 1-2 days of storage capacity. Factor in fire protection requirements if applicable.