How to use this calculator
- Enter or choose nutrient rate.
- Enter or choose rate unit.
- Enter or choose nutrient content of the product.
- Enter or choose field area.
- Enter or choose area in.
- The product for the field updates as you type. Use Copy result or Share to keep it.
Method
Product rate = Nutrient rate ÷ (Nutrient % ÷ 100); Product for field = Product rate × Area
- Nutrient rate
- kg or lb of nutrient per unit area
- Nutrient %
- guaranteed analysis of the product
Worked example
- Product rate = 100 ÷ 0.46 = 217.39 kg/ha (87.98 kg/acre).
- For 2 ha: 217.39 × 2 = 434.78 kg, or 10 bags of 45 kg (9.66 rounded up).
To apply 100 kg N/ha as urea you need 217.4 kg urea per hectare: 434.8 kg, or 10 bags of 45 kg, for 2 ha.
What the result means
Use the product rate to set your spreader. If you split the dose, divide the product rate by the number of applications.
Assumptions and limits
- The nutrient percentage is the guaranteed analysis on the label.
- Does not account for spreader overlap or losses; calibrate your spreader separately.
Questions
Is P on the label phosphorus or phosphate?
Labels give P₂O₅ and K₂O. Make sure your recommendation is in the same form; P × 2.291 = P₂O₅ and K × 1.205 = K₂O.
How do I convert lb/acre to kg/ha?
Multiply by 1.121. For example, 100 lb/acre is about 112 kg/ha.