Volume Calculator › Aquarium Volume

Aquarium Volume Calculator

Find a rectangular aquarium's volume in US gallons and litres from its length, width and height in inches.

Aquarium volume
in
in
in
Result
US gallons19.9 gal
Litres75.5 L
Quick answer
An aquarium holds length × width × height in cubic inches, and there are 231 cubic inches in a US gallon. A 24 by 12 by 16-inch tank is about 20 gallons, or 75 litres. This is the full volume; gravel, rocks and the water line below the rim make the real water a little less.

How it works

US gallons = length × width × height ÷ 231litres = cubic inches × 0.01639
length
tank length in inches
width
front-to-back depth in inches
height
tank height in inches

This is the tank's full capacity. Actual water volume is a bit less once you account for substrate, decorations and filling below the rim.

Frequently asked questions

How many gallons is a 24x12x16 tank?

About 20 US gallons.

How many cubic inches in a gallon?

231 for a US gallon.

How do I convert to litres?

Multiply cubic inches by 0.01639, or US gallons by 3.785.

Is the real water volume less?

Yes, gravel, rocks and the gap below the rim reduce it slightly.