Calculate aquarium volume

Calculate the litres below an aquarium’s water line and the approximate mass of that fresh water.

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ToolAquarium Volume Calculator
Input
Output
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Preview

How it works

Internal length, width, and height form a cuboid in cubic centimetres, and division by 1,000 converts that capacity to litres. The water-line percentage scales the full height before volume is reported, and one litre is treated as approximately one kilogram for the water-only mass.

Formula
litres = length cm × width cm × height cm ÷ 1,000 × fill percentage ÷ 100
  • Use the space inside the glass rather than the manufacturer’s external cabinet or nominal-capacity dimensions.
  • Every dimension and the water line are explicit because rim clearance, substrate depth, and tank proportions differ.

Worked example

A 60cm by 30cm by 36cm tank
Filled to 90%
Input
											Length cm: 60
Width cm: 30
Height cm: 36
Fill percent: 90
Output
												Volume litres: 58.32
Water weight kg: 58.32

When to use this

Filter turnover is matched to tank litres, dechlorinator labels dose replacement water by volume, and heater tables combine water volume with the required temperature rise.

Edge cases

  • External glass dimensions include wall thickness and overstate the water space; only the entered internal dimensions are multiplied.
  • A tank filled below its rim is reduced by the entered water-line percentage instead of being reported at full cuboid capacity.
  • Rock, wood, substrate, filters, and pipework displace water, but no generic displacement is invented; subtract a measured displacement separately.