Aquarium Volume Calculator – Gallons & Liters
Knowing your aquarium’s exact volume is essential for correct doses of water treatments and medications, and understanding how many fish your tank can support.
Aquarium Volume Calculator
Common Aquarium Sizes
| Tank | Dimensions (L×W×H in) | Volume |
|---|---|---|
| 5 Gallon | 16×8×10″ | 5 gal / 19 L |
| 10 Gallon | 20×10×12″ | 10 gal / 38 L |
| 20 Gallon Long | 30×12×12″ | 20 gal / 76 L |
| 55 Gallon | 48×13×21″ | 55 gal / 208 L |
Frequently Asked Questions
How many fish per gallon?
General rule: 1 inch of fish per gallon. But research your specific species — bioload and behavior matter more.
Why know my tank volume?
To correctly dose water conditioners, medications, fertilizers, and to choose the right filter and heater.
Gallons to liters?
Multiply US gallons by 3.78541. A 55-gallon tank ≈ 208 liters.