Aquarium & Fish
Calculate tank volume, fish stocking levels, CO2, fertilizers, and water changes for your aquarium.
Fish Tank Volume Calculator
Calculate the exact volume of your aquarium in gallons and liters.
Aquarium Stocking Calculator
Find out how many fish your aquarium can safely hold using the inch-per-gallon rule.
Aquarium CO2 Calculator
Calculate the ideal CO2 concentration for your planted aquarium using pH and KH.
Aquarium Fertilizer Dosing Calculator
Calculate the correct fertilizer dose for your planted aquarium by tank volume.
Aquarium Water Change Calculator
Calculate how much water to change and how long it takes to reach your target nitrate level.
Aquarium Calculators Guide
Successful fishkeeping depends on precise measurements. Incorrect dosing of medications, fertilizers, or CO2 can harm or kill your fish and plants. Use these calculators to dose accurately and maintain healthy water parameters.
Remember that all calculators work from your actual water volume — not your tank's labeled capacity. Measure your true water volume using the dimensions of your tank and subtract for substrate, decorations, and fill level. A 55-gallon tank typically holds 45–50 gallons of actual water.