The Aquarium Volume Calculator finds the water capacity of your fish tank so you know exactly how much water, filtration, and treatment products you need. Select your tank shape (rectangular, cylindrical, bow front, and more), enter the dimensions and optional fill depth, and choose your measurement unit to get the volume in US gallons, UK gallons, liters, and cubic inches.
US Gallons
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UK Gallons
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Liters
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Cubic Inches
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Accurate water volume calculations are crucial for proper fish stocking, filtration sizing, medication dosing, and maintaining stable water chemistry. Overcrowding can lead to poor water quality and stressed fish.
Select your tank shape and enter the dimensions. For rectangular tanks, multiply length × width × height. For cylindrical tanks, use π × radius² × height. The calculator automatically converts between units and accounts for different tank shapes.
Yes, tank shape significantly affects volume calculations. A bow front tank holds more water than a standard rectangular tank of the same dimensions due to its curved front glass. Corner and hexagonal tanks have their own specific volume formulas.
A general rule is 1 inch of fish per gallon for small fish, but this varies by species, filtration, and maintenance. Research specific fish requirements and consider adult size, bioload, and compatibility when stocking your tank.
Yes, if you don't fill your tank completely to the top. Most aquariums are filled to about 1-2 inches below the rim. Enter your actual water depth in the fill depth field for the most accurate volume calculation.
US gallons are smaller than UK gallons. 1 US gallon equals 3.785 liters, while 1 UK gallon equals 4.546 liters. This calculator provides both measurements for international compatibility.
The calculations are mathematically accurate for standard tank shapes. However, actual capacity may be slightly less due to substrate, decorations, equipment, and the fact that tanks aren't filled completely to the brim.
This calculator works for common aquarium shapes. For irregular or custom shapes, choose the closest standard shape or break the tank into multiple geometric sections and calculate each separately.