Fish Tank Volume Calculator in Litres

Calculating fish tank volume in litres

Measure length, width and height in centimetres, multiply them for cubic centimetres, then divide by 1000 to get litres. A 60 by 30 by 30 cm tank equals 54,000 cubic centimetres, or 54 litres.

How to work out the litres in a fish tank

1. Measure the inside length, width and height in centimetres. Centimetres give the cleanest maths for litres.
2. Multiply the three numbers to get cubic centimetres.
3. Divide by 1,000. One litre is exactly 1,000 cubic centimetres.

Example: a tank that is 80 x 35 x 40 cm holds 80 x 35 x 40 = 112,000 cubic centimetres, which is 112 litres.

If you measured in other units, the calculator converts for you, but the rules are:

• Millimetres: multiply and divide by 1,000,000
• Inches: multiply and then multiply by 0.0164 (or divide US gallons by 0.264)
• Feet: multiply and then multiply by 28.3

US gallon tanks in litres

Tanks sold in the US are named in US gallons. To turn a gallon size into litres, multiply by 3.785.

These are the litres the name implies. The real figure for a given tank can be a little higher or lower, because the gallon names are rounded. Measure your own tank and use the calculator above for the exact number.

If your tank was sold in UK gallons, multiply by 4.546 instead. A 20 UK gallon tank is about 90.9 litres, not 75.7.

Worked example with glass thickness

A common European tank is 60 x 30 x 30 cm on the outside. That is 54 litres. With 6 mm glass the inside is about 58.8 x 28.8 x 29.4 cm, which is 49.8 litres. Filled to 2 cm below the top, it holds about 46.4 litres. That is the number to use for water conditioner and medicine, and it is 14 percent less than the 54 litres printed on the box.

Litres, kilograms and stands

One litre of fresh water weighs about 1 kg, so the litre figure doubles as the weight of the water. A 112 litre tank carries about 112 kg of water before you add the glass, gravel and rock. Use the fish tank weight calculator to check the full load on your stand.

Quick answers

• How many litres is a 3 foot tank? A 3 x 1.5 x 1.5 foot tank (36 x 18 x 18 inches) is about 191 litres. A narrower 3 x 1 x 1 foot tank is about 85 litres. See the calculator in feet.
• How many litres in a 100 x 40 x 50 cm tank? 200 litres.
• Litres to US gallons? Divide by 3.785. Litres to UK gallons: divide by 4.546.

For the water left after gravel and decor, use the water volume calculator. For every shape’s formula, see how to find the volume of a fish tank.