Aquarium Volume Calculator
Calculate aquarium water volume in liters and gallons from length, width, and height. Free online fish tank volume calculator with dimension charts and unit conversions.
About This Calculator
The Aquarium Volume Calculator helps fish keepers, aquascapers, and pet store owners determine the exact water capacity of a rectangular aquarium. Simply enter the length, width, and height of your tank in centimeters, and the calculator instantly returns the volume in liters, US gallons, and UK imperial gallons.
The calculator uses the standard rectangular prism volume formula: Volume = Length × Width × Height. The result in cubic centimeters is divided by 1,000 to give liters. For US gallons, liters are multiplied by 0.264172, and for UK gallons by 0.219969.
Knowing your aquarium volume is essential for determining the correct heater wattage, filter flow rate, medication dosage, and the number of fish your tank can safely support. A good rule of thumb is 1 liter of water per 1 cm of adult fish length, though this varies by species and tank setup.
For accurate results, measure the internal dimensions of your tank (not the outer glass edges) and remember that decorations, substrate, and equipment will displace some water. We recommend subtracting 10-15% from the calculated volume to account for these elements.
Regional Notes
India: Aquarium sizes are typically measured in centimeters and liters. Common tank sizes include 60×30×30 cm (54L) and 90×45×45 cm (182L). Most aquarium equipment in India uses metric measurements.
United States: Aquariums are commonly measured in inches and gallons. A standard 20-gallon long tank measures 30×12×12 inches and a 55-gallon tank is 48×13×21 inches. This calculator accepts cm input but converts to US gallons for convenience.
United Kingdom: Aquariums are often measured in centimeters or inches with volume in liters or UK (imperial) gallons. A standard 4-foot tank measures approximately 120×38×38 cm (≈174L or 38 UK gallons).
Frequently Asked Questions
How do I calculate aquarium volume?
Measure the length, width, and height of your aquarium in centimeters, then multiply them together. For a rectangular tank, volume = length × width × height in cubic centimeters. Divide by 1000 to get liters, or multiply liters by 0.264172 to get US gallons.
What is the formula for aquarium water volume?
For a rectangular aquarium, the formula is Volume = Length × Width × Height. For example, a 60 cm × 30 cm × 40 cm tank has a volume of 72,000 cm³ which equals 72 liters or 19 US gallons.
How many fish can I keep in my aquarium?
A common rule of thumb is 1 liter of water for every 1 cm of adult fish length. For a 72-liter aquarium, you can keep approximately 72 cm of total fish length. However, this varies by species, and factors like filtration, plants, and tank shape also matter. Always research specific fish requirements.
How do I convert aquarium volume from liters to gallons?
To convert liters to US gallons, multiply the volume in liters by 0.264172. To convert to UK (imperial) gallons, multiply by 0.219969. For example, 72 liters = 19 US gallons = 15.8 UK gallons.
Does the shape of the aquarium affect the volume calculation?
Yes, different shapes use different formulas. A rectangular prism uses length × width × height. Cylindrical tanks use π × r² × height. Bow-front and corner tanks require more complex formulas. This calculator supports the most common rectangular aquarium shape.
Should I fill my aquarium completely to the brim?
No, you should leave about 2-5 cm of space at the top of the aquarium. This gap is needed for the filter, heater, and to prevent fish from jumping out. Subtract approximately 10-15% from the calculated volume to account for decorations, substrate, and equipment inside the tank.
What are standard aquarium sizes in liters?
Common aquarium sizes include: 20L (45 × 25 × 20 cm), 40L (60 × 30 × 25 cm), 72L (60 × 30 × 40 cm), 100L (80 × 35 × 40 cm), 180L (100 × 40 × 45 cm), and 250L (120 × 50 × 45 cm). These vary slightly by manufacturer but are good reference points for choosing a tank.
Is this aquarium volume calculator free to use?
Yes, this aquarium volume calculator is completely free to use with no registration or download required. You can share your calculations via the URL which saves your input values for easy reference.