Cannabis Nutrient Calculator

Cannabis plants require three primary macronutrients — Nitrogen (N), Phosphorus (P), and Potassium (K) — in different ratios depending on their growth stage. These are expressed as the NPK ratio on fertilizer labels.

During vegetative growth, plants need high nitrogen (3-1-2 ratio) to fuel rapid leaf and stem development. During flowering, the ratio shifts to high phosphorus and potassium (1-3-2) to support bud formation, terpene production, and resin development.

pH determines nutrient availability. In soil, cannabis absorbs nutrients best at pH 6.0–6.8. In hydroponic and coco coir systems, the optimal range is 5.5–6.2. Incorrect pH is the single most common cause of nutrient deficiencies — even when nutrients are present in the solution, they become locked out if pH drifts too far.

EC (Electrical Conductivity) measures the total dissolved salts in your nutrient solution and indicates feeding strength. PPM (Parts Per Million) is another way to express the same measurement. Most meters can display either unit.

The recommendations from this calculator provide general guidelines. Every strain responds slightly differently, so always monitor your plants and adjust based on what they are telling you. Slight leaf tip burn means you are at the upper edge — a small amount is acceptable but back off if it progresses.