Aquarium Calculators

Three free tools, all using the same conservative, transparent methods as our guides.

How many fish can your tank hold? Bioload-based stocking level with group, temperature and compatibility warnings for 44 species.

The right heater wattage for your tank size and room temperature — and the safer two-heater option.

Any percentage turned into exact gallons, litres and buckets, with a quick-reference table for common tanks.

How many gallons is your tank, from its measurements — plus why footprint matters as much as volume.