Hydroponic Nutrient Calculator

About this calculator

Two-part hydroponic nutrients (a “Part A” and “Part B” that must be added separately to avoid precipitating in concentrated form) are dosed by multiplying the reservoir volume by the manufacturer's recommended dose rate per liter or gallon — for example, brands like General Hydroponics' Flora series typically call for roughly 2–3 mL per gallon of each part during the seedling stage, rising to around 8–10 mL per gallon during bloom.

This calculator scales that dose rate to your specific reservoir size and returns the milliliters of each part to add. Hydroponic and soilless growers — from hobbyist indoor gardeners to commercial greenhouse operators — use it whenever they mix a new reservoir batch, then typically confirm the resulting nutrient strength with an EC (electrical conductivity) or PPM (parts-per-million) meter before dosing plants.