How to Calculate Aquarium Volume
To find your aquarium's volume, measure the internal dimensions of your tank (length × width × height) in inches or centimeters. Our calculator automatically converts to US gallons and liters.
For rectangular tanks, the formula is simple: Length × Width × Height ÷ 231 = Gallons. For bowfront, cylindrical, and hexagonal tanks, the calculator applies the correct geometric formula.
Why Tank Volume Matters
Knowing your exact tank volume is essential for dosing medications, adding water conditioner, calculating heater wattage, and determining how many fish your tank can support. Overestimating volume can lead to under-dosing treatments, while underestimating can cause overdoses.
Standard Aquarium Sizes
Most aquariums follow standard sizes: 5, 10, 20, 20 long, 29, 40 breeder, 55, 75, 90, 100, 125, and 150 gallons. Check our complete tank size guide for exact dimensions and weight information for each standard size.