Hydroponic Calculators
Precision tools for better yields — nutrients, EC, pH, VPD, reservoir sizing, and crop presets.
Nutrient Calculator
EC → PPM Converter
pH Adjustment
Always adjust slowly in small increments and re-test before adding more.
VPD CalculatorAdvanced
Reservoir Size
Based on 10L per plant — a safe minimum for most leafy greens and herbs.
Crop Guide
Common Questions
Calculator FAQs
How do I convert EC to PPM for hydroponics?
Multiply your EC value by 500 (North American standard) or 700 (European standard). For example, EC 2.0 = 1000 PPM on the 500 scale or 1400 PPM on the 700 scale. Use the EC → PPM calculator above to convert instantly.
What is the ideal EC for hydroponic lettuce?
Lettuce grows best at an EC of 1.2–1.8 mS/cm (600–900 PPM on the 500 scale). Lower EC encourages leafy growth; higher EC can cause tip burn.
What pH should hydroponic water be?
Most hydroponic crops thrive at a pH between 5.5 and 6.5. Leafy greens prefer 6.0–7.0, while fruiting plants like tomatoes do best at 5.5–6.5. Use the pH Adjustment calculator to estimate how much pH Up or pH Down to add.
What is VPD and why does it matter in hydroponics?
VPD (Vapour Pressure Deficit) measures the difference between the moisture in the air and how much moisture the air can hold. The ideal VPD for most hydroponic crops is 0.8–1.2 kPa. Too low causes mould; too high stresses plants and reduces uptake.
How big should a hydroponic reservoir be?
A safe rule of thumb is 10 litres per plant for most leafy greens and herbs. A 6-plant system needs at least a 60-litre reservoir. Larger reservoirs are more stable and require less frequent top-ups.