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Aquarium Calculators

Aquarium Volume Calculator

Tank volume in litres and gallons, with the real water volume after substrate.

Enter values

Results update as you type.

Result

Actual water volume

187 litres

Always dose medications on the real water volume — over-dosing on the nominal figure is a common way to lose fish.

Nominal tank volume
240 litres
In US gallons
49.39
In imperial gallons
41.13
Water depth
41 cm
Full weight with water
247 kg
including glass and substrate
Nominal volume that is actually water
77.9%

About the Aquarium Volume Calculator

A tank’s nominal size and its actual water volume are different things: substrate, rocks and the gap below the rim easily take 15% of it. Getting the real volume right matters because every dose of medication and every stocking rule depends on it.

Also known as: fish tank volume, tank litres calculator, aquarium gallons, how many litres is my tank.

How to use this calculator

  1. Enter length, width, height, substrate depth and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

litres = length × width × water depth ÷ 1000

Worked example

Using the values pre-filled in the calculator above:

  • Length = 120 cm
  • Width = 40 cm
  • Height = 50 cm
  • Substrate depth = 6 cm
  • Gap below the rim = 3 cm
  • Decorations and rock = 5 %

the calculator returns:

  • Actual water volume: 187 litres
  • Nominal tank volume: 240 litres
  • In US gallons: 49.39
  • In imperial gallons: 41.13