Urea, DAP and MOP Fertilizer Calculator

Convert an existing nutrient application plan into quantities of urea, DAP and MOP. Enter the target application in kilograms per hectare, using N, phosphate as P₂O₅, and potash as K₂O. This tool calculates product quantities; it does not decide the nutrient rates a crop needs.

Calculate fertilizer product quantities

Assumed grades: urea 46-0-0, DAP 18-46-0, and MOP 0-0-60. Check the actual bag labels before using the result.

The prefilled values are an arithmetic example, not a crop recommendation.

How the calculation works

  • DAP (kg/ha) = P₂O₅ application target ÷ 0.46.
  • N supplied by DAP = DAP quantity × 0.18.
  • Urea (kg/ha) = the positive remaining N application target ÷ 0.46.
  • MOP (kg/ha) = K₂O application target ÷ 0.60.
  • Total product quantity = product rate × field area in hectares.

For the example targets of 120 kg N, 60 kg P₂O₅ and 40 kg K₂O per hectare, the calculation gives approximately 209.83 kg urea, 130.43 kg DAP and 66.67 kg MOP per hectare. These quantities change when the targets or product grades change.

Use application recommendations, not raw soil-test numbers

Enter the fertilizer application targets from an appropriate crop nutrient plan. A soil-test concentration is not automatically a nutrient credit in kg/ha. Do not directly subtract laboratory readings, including values in ppm, from these targets. Use the laboratory’s interpreted recommendation and relevant local guidance.

A fixed combination of products can oversupply a nutrient. For example, meeting a phosphorus target with DAP also adds nitrogen. The tool flags this situation, rather than promising balanced fertilization. Product suitability, placement, timing, split applications and crop response need separate consideration.

References and related tools

Read Penn State Extension’s soil-test report guidance and guide to converting recommendations to fertilizer products. University of Minnesota Extension explains urea fertilizer. Regional recommendations must be matched to your own crop and location.

For one product with a different nutrient analysis, use the Fertilizer Dosage Calculator. To assess a compound NPK product against several nutrient targets, use the NPK Fertilizer Calculator.

Subject review: Dr. Ijaz Ali, Soil Scientist. Reviewed the fertilizer nutrient arithmetic. Software and calculator implementation: BlogAgri.