Enter your reservoir size, the label dose in ml per gallon and how many parts your nutrient series has to get exact ml per part.
The formula
Dose per part = gallons × ml per gallon; multi-part series (A/B, or 3-part lines) repeat that per bottle. The calculator also converts to teaspoons for small reservoirs where syringes feel like overkill.
Worked example
A 20-gallon reservoir on a two-part nutrient dosed at 5 ml per gallon: 100 ml of part A and 100 ml of part B — 200 ml total, or about 20 teaspoons per part.
Dosing without drama
Always follow the label’s stage chart — seedlings take a quarter to half the full dose, and “more” is the most common way to burn a crop. Add parts separately, stirring between them; concentrated A and B poured together precipitate and lock out calcium. If you run an EC or PPM meter, treat the label dose as the starting point and let the meter make the final call, topping up with plain water first when readings drift high. Everything runs in your browser; nothing is stored.