Stocking Calculator
Enter your tank size and fish, get an instant stocking percentage, over/understocked verdict, filtration target, and compatibility warnings.
Quick toolFilter Size Calculator
Tank gallons in, recommended filter flow (GPH) out — based on the 4× turnover rule of thumb.
Quick toolHeater Wattage Calculator
Find the right heater size from your tank volume and how far you need to raise the water temperature.
Why these tools exist
Most new fishkeeping problems trace back to two early mistakes: putting too many fish in too little water, and under-sizing the filter and heater. TankStocked turns the hobby's common rules of thumb into quick, honest calculators so you can plan a stable tank instead of guessing.
Every tool shows its math and its limits. These are planning aids — your filtration, maintenance habits, and the specific species you keep matter just as much as any number.
Popular guides
Affiliate disclosure · We may earn a commission from qualifying purchases. Our calculators and guidance are not influenced by any product link.