Aquarium calculators
A full set of freshwater aquarium tools. Each one runs in your browser and gives gallons first, with liters in brackets where it helps.
Tank volume calculator
Net water volume after substrate and rim gap, in gallons and liters.
Stocking calculator
Percent stocked and warnings from a library of common species.
Heater wattage calculator
Recommended heater size for your volume and temperature gap.
Water change calculator
How many gallons to change to reach a target nitrate level.
Filter turnover calculator
Turnover per hour against the target for your stocking level.
Tank weight calculator
Full loaded weight and pounds per square foot on your floor.
Substrate calculator
Gravel, sand or aqua soil needed, in pounds and liters.
Glass thickness calculator
Safe glass thickness and safety factor for your tank.
Salt mix calculator
Marine salt to reach a target salinity for brackish or saltwater.
Light calculator
Lumens and LED wattage for low, medium or high light plants.
Setup cost calculator
One time cost of starting a tank, with cost per gallon.
How to use these tools
Start with the tank volume calculator. Almost every other tool depends on knowing your true water volume, which is smaller than the printed tank size once you account for substrate and the gap you leave below the rim. Take that net gallons figure and carry it into the stocking, heater, water change, turnover and weight calculators for consistent results.
These calculators cover freshwater tanks. Marine and brackish systems have different needs for salinity, flow and livestock, so the stocking and heater guidance here will not map cleanly onto them.