Aquarium calculators
Each calculator runs entirely in your browser and shows the formula behind every number, with a worked example and the assumptions that could make it wrong for your tank. We would rather you understand the estimate than trust it blindly.
Stocking & Bioload Planner
Estimate net water volume, bioload and compatibility for a planned community, with every formula shown.
Open calculatorFishless Cycle Ammonia Dosing Calculator
Work out how much household ammonia or ammonium chloride reaches your target ppm, with unit conversions.
Open calculatorHow we build calculators
Every tool starts from published chemistry or widely used husbandry references, which are cited on the tool page. Where a tool relies on a rule of thumb rather than a physical law, such as the bioload model in the stocking planner, the page says so and explains how to check the result against your own water tests. If you find a calculation error, please contact us; corrections are logged under our editorial policy.