Aquarium calculators
The sizing questions every tank runs into, answered with real numbers: how big it is, the heater and filter it needs, and the exact dose to add.
Aquarium volume calculator
How many gallons is your tank? Enter the dimensions for volume in gallons and litres, plus water weight — the number every other decision starts from.
Open the tool →Heater wattage calculator
Size the heater from tank volume and the temperature rise over your coldest room temp, with the reviewed heaters that cover it.
Open the tool →Filter GPH calculator
Work out the filter flow rate (GPH) your tank needs from size and stocking, with real-world headroom for hang-on-back derating.
Open the tool →Water conditioner dosing calculator
The exact dose of Prime, API, Fritz and more for your water volume — each worked out from the manufacturer's own stated rate.
Open the tool →Stocking calculator
A realistic estimate of how many fish your tank can hold, by tank size and adult fish size — not the one-inch-per-gallon myth.
Open the tool →