Calculate stock solution dilution ratios, target EC, and pH ranges for hydroponic nutrient management. Mix precise nutrient solutions for soilless growing.
Hydroponic systems deliver nutrients directly to plant roots through water, making precise nutrient management essential. Stock solutions — concentrated fertilizer mixes — are diluted to a working strength measured by Electrical Conductivity (EC) in mS/cm or Total Dissolved Solids (TDS) in ppm.
This calculator helps you determine the dilution ratio to reach your target EC from a stock solution, and converts between EC and TDS. It also shows the recommended EC and pH ranges for common hydroponic crops.
Accurate nutrient management is the single most impactful factor in hydroponic crop quality and yield — small errors compound quickly in soilless systems. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process. This tool handles all the complex arithmetic so you can focus on interpreting results and making informed decisions based on accurate data.
Unlike soil, which buffers nutrient imbalances, hydroponic systems have no safety net. An incorrect dilution can immediately damage roots through salt burn or starve plants from deficiency. This calculator helps you mix precisely every time. Having a precise figure at your fingertips empowers better planning and more confident decisions. Manual calculations are error-prone and time-consuming; this tool delivers verified results in seconds so you can focus on strategy.
Dilution Ratio = Stock EC / Target EC Parts Water = Dilution Ratio − 1 (for 1 part concentrate) TDS (ppm) ≈ EC (mS/cm) × 500 (using 500 scale) or TDS (ppm) ≈ EC (mS/cm) × 700 (using 700 scale)
Result: 1:24 dilution ratio
A stock solution at 50 mS/cm diluted to a target of 2.0 mS/cm: 50 / 2.0 = 25× total volume. That's 1 part stock to 24 parts water. At EC 2.0 mS/cm, TDS ≈ 1,000 ppm (500 scale).
Daily monitoring of EC and pH is essential in hydroponics. EC rises as plants take up water faster than nutrients (concentrate solution). EC drops as plants take up nutrients faster than water (dilute solution). Top off with plain water or weak solution to maintain target EC.
The Hoagland solution is a classic research formula. Commercial two-part (A+B) or three-part (Grow/Micro/Bloom) systems are more practical. Each provides a complete nutrient package when mixed at the recommended ratios. Adjust ratios for vegetative vs. flowering growth stages.
Start with low-EC source water (< 0.3 mS/cm). Reverse osmosis (RO) water gives a clean baseline. If using well or tap water, test for baseline EC, alkalinity, and specific ions (calcium, sodium, chloride) to account for their contribution to the final solution.
Electrical Conductivity (EC) measures the total ion concentration in a solution. Higher EC means more dissolved nutrients. It doesn't tell you which nutrients are present, just the overall strength. Measured in mS/cm (millisiemens per centimeter).
EC measures conductivity directly. TDS (Total Dissolved Solids) is estimated from EC using a conversion factor — typically 500 or 700 depending on the meter manufacturer. EC is the more universal standard in professional hydroponics.
Calcium sulfate and calcium phosphate are relatively insoluble. If calcium and sulfate or phosphate ions are concentrated together in one stock, they precipitate out of solution. Separate A (calcium + nitrate) and B (phosphate + sulfate + micronutrients) stocks prevent this.
Most hydroponic crops perform best at pH 5.5-6.5. Below 5.0, micronutrient toxicity can occur. Above 7.0, iron and other micronutrients become unavailable. Check pH daily and adjust as needed.
In recirculating systems, change every 1-2 weeks or when EC drifts significantly from target. In drain-to-waste systems, fresh solution is delivered each irrigation. Monitor EC and pH trends to determine change frequency.
Most garden fertilizers are designed for soil and may not dissolve fully or contain the right nutrient ratios for hydroponic use. Use fertilizers specifically formulated for hydroponics with fully soluble salts and complete micronutrient packages.