Hydroponic Nutrient Mix Calculator
Mixing hydroponic nutrients correctly requires knowing how much fertilizer to dissolve per liter of water to reach your target electrical conductivity (EC). This calculator uses the standard approximation that 1 gram per liter of complete hydroponic fertilizer raises EC by approximately 1.2 mS/cm (the EC factor varies by fertilizer formulation; adjust in the EC factor field to match your product's specification). The tool also calculates total nutrient weight for a larger reservoir volume. Always verify the final EC with a calibrated EC meter after mixing.
Hydroponic nutrient formula
Dose (g/L) = Target EC (mS/cm) / EC factor (mS/cm per g/L)
Total nutrient (g) = Dose (g/L) x Reservoir volume (L)
The EC factor depends on the specific fertilizer salts. A typical complete hydroponic nutrient blend is approximately 1.1 to 1.3 mS/cm per g/L. Pure potassium nitrate is about 1.15 mS/cm per g/L; calcium nitrate is about 1.1 mS/cm per g/L. Consult your nutrient manufacturer or published fertilizer salt tables for exact values.
Target EC by crop stage
- Seedlings and clones: 0.5 to 1.0 mS/cm (dilute to avoid root burn).
- Vegetative stage, leafy greens: 1.0 to 2.0 mS/cm.
- Fruiting vegetables (tomatoes, peppers): 2.0 to 3.5 mS/cm.
- Herbs (basil, mint): 1.0 to 1.6 mS/cm.
- Strawberries: 1.4 to 2.0 mS/cm.
Hydroponic nutrient calculator: frequently asked questions
What is EC in hydroponics?
EC (electrical conductivity) measures the concentration of dissolved salts (nutrients) in water, expressed in millisiemens per centimeter (mS/cm) or microsiemens per centimeter (uS/cm). Higher EC means more dissolved nutrients. Most vegetables grow well at EC 1.5 to 2.5 mS/cm.
How do nutrients affect EC?
Every gram of dissolved fertilizer salt contributes to EC. A common approximation for mixed complete fertilizers is that 1 gram per liter of typical hydroponic nutrient concentrate raises EC by approximately 1.0 to 1.3 mS/cm, though exact values depend on the salt composition.
What EC should I target for different crops?
Leafy greens (lettuce, spinach, herbs): 1.0 to 1.8 mS/cm. Tomatoes, peppers: 2.0 to 3.5 mS/cm. Cucumbers: 1.7 to 2.5 mS/cm. Strawberries: 1.4 to 2.0 mS/cm. These ranges are consistent with university hydroponic research publications.
How do I mix a two-part hydroponic nutrient?
Two-part nutrients (Part A and Part B) must be diluted separately before combining to prevent precipitation. Add Part A to water first, mix well, then add Part B. Never mix concentrates directly together. Follow the manufacturer's ratios and measure EC after mixing.
Does temperature affect EC readings?
Yes. EC meters are temperature-compensated to 25 degrees Celsius (77 F). A solution's EC increases by roughly 2 percent per degree Celsius as temperature rises. Most modern EC meters have automatic temperature compensation (ATC). Calibrate with a 1.41 mS/cm standard solution regularly.
Official sources
- USDA Agricultural Research Service, controlled environment agriculture: ars.usda.gov.
- USDA National Institute of Food and Agriculture: nifa.usda.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.