N-P-K Nutrient Calculator — Actual Nitrogen, Phosphorus & Potassium
Enter the weight of fertilizer you are applying and the three N-P-K numbers from the bag (the percentages of nitrogen, phosphorus as P₂O₅, and potassium as K₂O). The calculator shows the actual weight of each nutrient component. Note: the P and K numbers on a fertilizer bag are expressed as P₂O₅ and K₂O, not elemental P and K.
What this calculator determines
It calculates the actual weight of nitrogen, phosphate (P₂O₅), and potash (K₂O) in a given weight of fertilizer from its N-P-K percentages.
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Examples
10 lb of 10-10-10
10 lb, 10-10-10
Calculation
- N: 10 × 10% = 1 lb
- P₂O₅: 10 × 10% = 1 lb
- K₂O: 10 × 10% = 1 lb
1 lb N, 1 lb P₂O₅, 1 lb K₂O
Assumptions & Conventions
- P and K as oxides
- The P and K numbers on a fertilizer bag are expressed as P₂O₅ and K₂O, not elemental phosphorus and potassium; this calculator reports the oxide components as labeled.
- Formula
- Nutrient weight = fertilizer weight × (percentage ÷ 100), applied to each of N, P₂O₅, and K₂O.