Fish Aquarium Calculators — Pets
Set up a healthy tank with the right equipment and stocking levels. The fish tank size calculator matches volume to your fish, the stocking calculator applies inch-per-gallon and bioload guidance to avoid overcrowding, and the filter and heater size tools spec turnover rate and wattage for your water volume. Each shows the reasoning, helping new and experienced aquarists keep water stable and fish thriving.
All Fish Aquarium Calculators
Calculate the correct filter GPH rating for your aquarium from tank volume and fish load.
Calculate the correct heater wattage for your aquarium from tank volume and temperature differential.
Determine how many fish your aquarium can safely hold using the inch-per-gallon and bioload rules.
Calculate the minimum tank size from fish species, quantity, and adult size.
About Fish Aquarium Calculators
Set up a healthy tank with the right equipment and stocking levels. The fish tank size calculator matches volume to your fish, the stocking calculator applies inch-per-gallon and bioload guidance to avoid overcrowding, and the filter and heater size tools spec turnover rate and wattage for your water volume. Each shows the reasoning, helping new and experienced aquarists keep water stable and fish thriving.
Whether you need to solve a one-time problem or verify your own calculations, these free tools cover the most common fish aquarium scenarios. All results are computed in your browser — no data is sent to any server.
What You Can Calculate
This section includes 4tools: Aquarium Filter Size Calculator, Aquarium Heater Size Calculator, Fish Stocking Calculator, Fish Tank Size Calculator. Each calculator is free to use with no signup required.