Knowing the volume of water that you tank can hold is important to know for many reasons including knowing how much of a dosage to apply for a supplement, how much livestock you can accommodate, and what type of equipment you need (ie; protein skimmers are typically rated by tank size). You can use the form below to quickly and easily calculate the volume of any empty square or rectangular aquarium. Please be sure to take water displacement into account for live rock, sand beds and decorations. Bookmark this page and come back as often as you need when you need to determine the water volume of any square or rectangular aquarium!