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NPK Fertilizer Rate Calculator

Calculate the quantity of fertilizer product needed to deliver a target nitrogen (N), phosphorus (P₂O₅), and potassium (K₂O) rate.

Nitrogen requirement in kg per hectare (from soil test or crop guideline)
Urea = 46% N · Ammonium Nitrate = 34% · Ammonium Sulfate = 21%
Triple Superphosphate = 46% · DAP = 46% P₂O₅ (also 18% N)
Muriate of Potash (KCl) = 60% K₂O · Sulfate of Potash = 50%

Results

N Fertilizer Needed260.9 kg total
P Fertilizer Needed0.0 kg total
K Fertilizer Needed0.0 kg total
N Rate per Hectare260.9 kg/ha

📖What is it?

Fertilizer rate calculation converts nutrient requirements (in pure N, P₂O₅, or K₂O) into the weight of a specific fertilizer product. Formula: product weight = nutrient required ÷ (nutrient concentration / 100). Nutrient requirements come from soil tests and crop uptake guidelines.

🎯How to use

Enter the target nutrient rates in kg/ha for N, P₂O₅, and K₂O (from soil test recommendations). Enter the nutrient content percentage of each fertilizer product you plan to use. Enter the field area. Leave a percentage at 0 if that nutrient is not in your chosen product — it will return 0 product needed.

💡Example scenario

Wheat crop needing 120 kg N/ha using Urea (46% N): product rate = 120/0.46 = 260.9 kg Urea/ha. Over 5 hectares: 1,304 kg Urea total. For 60 kg P₂O₅/ha using Triple Super (46% P₂O₅): 130.4 kg/ha = 652 kg total.

🏆Pro tip

Split nitrogen applications improve efficiency and reduce loss. Apply 1/3 at planting and 2/3 at key growth stages (tillering for wheat, V6 for corn). Inhibitor-treated ureas (NBPT) reduce ammonia volatilisation by up to 30% in warm, moist conditions. Always base nutrient applications on soil test results, not blanket recommendations.