Calculate aquarium volume in gallons, liters, cubic feet, and cubic meters. Estimate usable fish tank water volume after fill level, substrate, rocks, decor, and equipment displacement. Use this aquarium volume calculator for freshwater tanks, saltwater tanks, reef tanks, planted tanks, nano tanks, turtle tanks, and custom fish tanks.
Rectangular tank:
The calculator multiplies length, width, and height, then converts cubic inches into gallons and liters.
Bowfront tank:
The calculator estimates rectangular tank volume plus an added curved-front volume adjustment.
Cylindrical tank:
Enter diameter and height to estimate round aquarium or cylinder tank volume.
Usable water volume:
Fill level, substrate, decor, and equipment displacement are subtracted to estimate actual water volume.
An aquarium volume calculator helps estimate actual fish tank water volume, which is important for stocking, cycling, filtration, medication, dosing, water changes, and saltwater mixing.
It can be useful for freshwater tanks, reef tanks, planted tanks, saltwater tanks, turtle tanks, nano tanks, bowfront tanks, cylinder tanks, and custom aquariums.
Your result shows total tank volume, usable water volume, gallons, liters, cubic feet, cubic meters, water weight, substrate displacement, decor displacement, water change volume, monthly water change total, salt mix amount, and dosing amount.
For a rectangular tank, multiply length by width by height in inches, then divide by 231 to get US gallons.
Inside dimensions are more accurate because glass thickness reduces the actual water-holding space.
Substrate, rocks, driftwood, decor, filters, equipment, and not filling the tank to the rim all reduce actual water volume.
Water volume affects stocking, filtration, cycling, medication dosage, fertilizer dosing, salt mix, water changes, and temperature stability.