Calculate aquarium volume in liters and gallons for rectangular and cylindrical tanks. Free online fish tank volume calculator with formula and FAQ.
The aquarium volume calculator determines the total water capacity of your fish tank in both liters and gallons. Knowing your exact tank volume is crucial for dosing medications, adding water conditioners, selecting appropriate filters and heaters, and determining how many fish your tank can safely support.
Rectangular: Volume = L × W × H (cm) ÷ 1000 = liters
Cylindrical: Volume = π × r² × H ÷ 1000 = liters
1 liter = 0.264 US gallonsFor rectangular tanks, multiply length × width × height in cm and divide by 1000 to get liters. For cylindrical tanks, use the diameter as the length field; the calculator uses π × radius² × height. Actual water volume is approximately 90% of total volume after accounting for substrate, decorations, and the water line not reaching the top.
| Input | Output |
|---|---|
| 60×30×40 cm rectangular | 72 liters (19.02 US gallons), ~64.8 liters actual water |
| 40×40×50 cm cylindrical | 62.83 liters (16.60 US gallons), ~56.55 liters actual water |
| 120×45×50 cm rectangular | 270 liters (71.33 US gallons), ~243 liters actual water |