Aquarium Volume Calculator
Convert tank dimensions in inches or centimeters to gallons and liters, with filled weight and common tank presets.
Processed locally in your browser — nothing is uploaded.
Aquarium Volume Calculator
Enter the tank's inside dimensions to see the volume.
About Aquarium Volume Calculator
Measure your tank's length, width, and height — inches or centimeters — and get its volume in gallons and liters, plus the water weight and a rough filled weight including glass and substrate. One-tap presets cover the common glass sizes from a 10-gallon up to a 75.
The filled weight matters more than people expect: a 55-gallon setup pushes past 500 lb, well beyond ordinary furniture.
Common uses
- Dose medication and water conditioner by true volume
- Check whether a stand or floor can take a tank's filled weight
- Verify a used tank's advertised size from its measurements
Example
Input
20 × 10 × 12 in
Output
10.4 gal / 39.3 L · ≈ 100 lb filled
Limitations
- Dimensions are treated as inside glass; measuring outside overstates volume slightly, more so on big tanks where glass runs 1/2″ or thicker.
- Substrate, rock, and low water lines all reduce true water volume.
Frequently asked questions
How do I calculate aquarium gallons from inches?
Multiply length × width × height in inches and divide by 231, the number of cubic inches in a US gallon. A 20 × 10 × 12 inch tank works out to 2,400 ÷ 231 ≈ 10.4 gallons.
How much does a full aquarium weigh?
Water alone weighs 8.345 lb per gallon, and glass, substrate, and decor add roughly 15% on top. A filled 55-gallon setup lands over 500 lb — beyond what typical furniture is built for, so check the stand and, for big tanks, the floor.
Is any of my tank data transmitted or kept?
No. The measurements you enter are calculated on right in your browser and never sent anywhere — nothing is stored once you close the page.
Why does my tank hold less water than its advertised size?
Advertised sizes are nominal outside dimensions, while water fills the inside — glass runs about 1/4 inch thick on small tanks up to 1/2 inch or more on 75-gallon-plus sizes. Substrate, rock, and the gap you leave at the top reduce true water volume further.