This simple form to convert the dimensions of your aquarium in inches or centimeters in both U.S. gallons, U.K. gallons, and liters. All you need is to measure your fish tank’s length (from side to side), width (from front to back of the tank), and height (from top to bottom of the tank), and you can figure out how much water your aquarium holds.
This conversion form can help you determine the appropriate tank population, and whether you have enough space for the fish you are planning on getting.
Aquarium Water Volume Calculator



A gallon is a measure of volume primarily used in the United States and commonly used in many other English speaking countries. Most other countries use “liters” – the metric unit of measure for volume.
The US gallon is used in the United States and is equal to exactly 231 cubic inches or 3.785411784 liters.
The Imperial gallon or UK gallon is used in the United Kingdom and is equal to approximately 277.42 cubic inches. Its exact value is defined as 4.54609 liters.
1 UK gallon is about 1.2 US gallons.
Gallons to Liters Conversion
1 US gallon = 0.83267384 UK gallon = 3.78541178 Liters
1 UK gallon = 1.20095042 US gallon = 4.54609188 Liters
1 Liter = 0.264172052 US gallon = 0.219969157 UK gallon