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Aquarium Volume Calculator (Litres and Gallons)

Knowing the real water volume matters for medicine doses, water changes, heater and filter size.

Metric (kg, cm, °C) Imperial (lb, in, °F)

Tank shape Length (or diameter for round tanks) (cm) Width (not needed for round tanks) (cm) Water height (cm)

Fill in the fields above to see the result.

Common questions

How much water should I change?

Most tanks do well with 10–25% every week, using conditioned water at the same temperature.

What size filter do I need?

Many keepers aim for a filter that moves 4–6 times the tank volume per hour; check the needs of your fish.

US or UK gallons?

A US gallon is 3.785 litres and a UK (imperial) gallon is 4.546 litres; the result shows both.