/ /NPK Fertilizer Calculator
NPK Fertilizer Calculator
Design custom NPK fertilizer blends by combining different fertilizer sources. Calculate the exact amounts of each source needed to meet your crop's nutrient requirements and minimize costs.
Inputs
Desired N (lbs/acre)
Desired P2O5 (lbs/acre)
Desired K2O (lbs/acre)
Soil Test N (lbs/acre)
Soil Test P (lbs/acre)
Soil Test K (lbs/acre)
Area Unit
Field Area (acres)
Results
N Applied (lbs/acre):0.00
P2O5 Applied (lbs/acre):0.00
K2O Applied (lbs/acre):0.00
N Coverage:0.0%
P Coverage:0.0%
K Coverage:0.0%
Blend Ratio (N-P-K):0.0-0.0-0.0
Total lbs/acre:0.00
Cost per Acre:$0.00
Total Cost:$0.00
Blend Note: Your custom blend has a ratio of 0.0-0.0-0.0. For 100.0 acres, total nutrients needed: N=0.0 lbs, P=0.0 lbs, K=0.0 lbs.
Target Check: N coverage (0%) is below target - increase N sources. P coverage (0%) is low. K coverage (0%) is low.
Fertilizer Sources
Name
N%
P%
K%
Lbs/acre
Name
N%
P%
K%
Lbs/acre
Name
N%
P%
K%
Lbs/acre
Unit Conversion: To convert lbs/acre of P2O5 to elemental P, multiply by 0.437. To convert lbs/acre of K2O to elemental K, multiply by 0.83. Your blend on elemental basis: P = 0.00 lbs/acre, K = 0.00 lbs/acre.
Related Calculators
References
Frequently Asked Questions
- How do I calculate NPK fertilizer blends?
- Calculate the amount of each fertilizer source needed by dividing the desired nutrient rate by the nutrient content of each source. For example, to supply 100 lbs of N using urea (46-0-0): 100 / 0.46 = 217 lbs of urea. Solve a system of equations when using multiple sources to meet all three N-P-K targets simultaneously.
- What are common fertilizer sources and their N-P-K values?
- Common sources: Urea (46-0-0), Ammonium Nitrate (34-0-0), DAP - Diammonium Phosphate (18-46-0), MAP - Monoammonium Phosphate (11-52-0), Potash (0-0-60), Triple Superphosphate (0-46-0), Ammonium Sulfate (21-0-0-24S), and blended fertilizers like 10-10-10 or 19-19-19.
- How do I convert P2O5 and K2O to elemental P and K?
- Elemental phosphorus (P) is about 43.7% of P2O5. To convert: P = P2O5 � 0.437. Elemental potassium (K) is about 83% of K2O. To convert: K = K2O � 0.83. Most fertilizer recommendations are given as P2O5 and K2O, so this conversion is mainly needed for scientific calculations.
- What is the best NPK ratio for my crop?
- Optimal NPK ratios vary by crop, growth stage, and soil conditions. Corn at planting: 1-2-1 or 1-1-1; corn at sidedress: high N (e.g., 3-0-0). Soybeans: 0-1-2 or 0-2-3. Wheat: 1-1-1 or 2-1-1. Vegetables: 1-2-2 for fruiting, 2-1-1 for leafy. Always base decisions on soil test results and yield goals.
- What is the difference between DAP and MAP fertilizer?
- DAP (18-46-0) contains 18% N and 46% P2O5. MAP (11-52-0) contains 11% N and 52% P2O5. DAP has higher N content and is more alkaline near the seed, which can affect germination. MAP is more acidic and safer for placement near seeds. DAP is generally cheaper per unit of P, but MAP offers better seedling safety.