Aquarium Volume Calculator
Enter your tank's inside dimensions to get exact volume in gallons and liters. Knowing your real water volume matters for dosing, water changes, and stocking.
Frequently Asked Questions
How do you calculate aquarium gallons?
Multiply length × width × height in inches, then divide by 231 (the number of cubic inches in a US gallon). For liters, multiply gallons by 3.785.
Why is my actual water volume less than the rated size?
Substrate, rocks, decorations, equipment, and the gap below the rim all displace water. Real water volume is usually about 85–90% of the tank's gross size — use that figure for dosing and stocking.