Aquarium volume calculator
Pick the shape of your tank and enter its inside size and the depth of the water. The calculator gives the volume in litres and US gallons and the weight of the water. Bow-front tanks are an approximation.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose metric or US units and the tank shape.
- Enter the inside dimensions and the depth of the water.
- Read the volume, in litres and gallons, and the weight of the water.
How it works
Rectangular: length × width × depth. Cylinder: π ÷ 4 × diameter² × depth. Bow front: (length × width + 2/3 × length × bulge) × depth. 1 US gallon = 3.785411784 L, and one litre of fresh water weighs about 1 kg.
Worked example
A tank 100 × 40 cm with 45 cm of water: 100 × 40 × 45 = 180,000 cm³ = 180 L = 47.6 US gallons. The water weighs about 180 kg (397 lb).
Tips
- Glass thickness is not included: measure inside the tank.
- For a hexagon or corner tank, use the closest simple shape and treat the result as a rough figure.
- Check that your stand and floor can carry the full weight.
Frequently asked questions
Should I measure inside or outside the glass?
Inside. The calculator does not subtract glass thickness, so measure the inside of the tank, and measure the depth of the water rather than the height of the glass.
How is a bow-front tank calculated?
As a box plus a parabola-shaped bulge on the front glass, with area 2/3 × length × bulge. Real bows are circular arcs, so treat the result as an estimate, a little different from the label.
How much does the water weigh?
Fresh water weighs about 1 kg per litre (8.3 lb per US gallon) at room temperature. The tank, gravel, rock, stand and equipment come on top of that.
Why is it less than the tank's stated size?
Tank sizes are nominal and are for the full glass volume. In use you leave a gap at the top, and gravel, rocks and decorations take up space, so a tank usually holds 10–20% less water than its label.