Aquarium Volume Calculator (Litres and Gallons)
Find how much water your fish tank holds in litres and gallons, and how much it weighs.
How to work out aquarium volume
Measure the tank, choose its shape, and the calculator gives the volume in litres, US gallons and UK gallons, with the weight of the water. Knowing the true volume matters for choosing a filter and heater, dosing water treatments and medicines, and deciding how many fish the tank can hold.
- Rectangular tank: volume = length × width × height.
- Cylinder tank: volume = π × radius² × height.
- Half cylinder tank: half of a cylinder with the same width.
- To litres: cubic centimetres ÷ 1,000, or cubic inches × 0.016387.
Worked example
A tank 60 cm long, 30 cm wide and 36 cm high:
- Volume: 60 × 30 × 36 = 64,800 cubic centimetres
- 64,800 ÷ 1,000 = 64.8 litres
- In US gallons: 64.8 ÷ 3.785 = 17.1
- In UK gallons: 64.8 ÷ 4.546 = 14.3
- Weight of the water: about 64.8 kg (142.9 lb)
In inches, a tank 20 × 10 × 12 is 2,400 cubic inches, which is 39.3 litres or 10.4 US gallons. This is the common “10 gallon” size.
Common tank sizes
| Size (L × W × H) | Litres | US gallons | UK gallons |
|---|---|---|---|
| 60 × 30 × 30 cm | 54 | 14.3 | 11.9 |
| 80 × 35 × 40 cm | 112 | 29.6 | 24.6 |
| 100 × 40 × 50 cm | 200 | 52.8 | 44.0 |
| 120 × 50 × 50 cm | 300 | 79.3 | 66.0 |
| 150 × 50 × 60 cm | 450 | 118.9 | 99.0 |
Real water volume is lower
- Fill level: water usually stops a few centimetres below the rim. Set the fill level to 90 or 95% to allow for it.
- Glass thickness: outside measurements include the glass. Measure the inside for a closer figure.
- Gravel, rocks and decorations: these take up space, often 10% or more of the tank.
For dosing medicines, use the lower, real water volume.
How much a full tank weighs
Fresh water weighs about 1 kilogram per litre (8.34 pounds per US gallon), and salt water is about 2.5% heavier. Add the weight of the glass, gravel, rocks and stand. A 200 litre tank can pass 250 kg in total, so check that the stand and the floor can carry it.
How to cite this page
CalcPulse. (2026). Aquarium Volume Calculator. https://calcpulse.com/aquarium-volume-calculator/
Frequently asked questions
How do I calculate the volume of my aquarium?
Multiply length by width by height. In centimetres, divide by 1,000 to get litres. In inches, divide by 231 to get US gallons.
How many litres is a 60 cm tank?
A standard 60 × 30 × 30 cm tank holds 54 litres to the brim, and a 60 × 30 × 36 cm tank holds 64.8 litres.
How many litres are in a US gallon?
One US gallon is 3.785 litres. One UK (imperial) gallon is 4.546 litres.
How much does a full aquarium weigh?
The water weighs about 1 kg per litre, or 8.34 lb per US gallon. Add the glass, gravel, rocks and stand for the total.
Why is the real water volume less than the calculated volume?
The tank is not filled to the brim, the glass takes up some of the outside measurement, and gravel and decorations displace water.
How do I measure a cylinder tank?
Measure the diameter across the widest point and the height, then use the Cylinder tab. The volume is π × radius² × height.
Last reviewed and updated by the CalcPulse team