# Fertiliser Application Rate Calculator

> Convert a nutrient rate (kg/ha or lb/acre) into the amount of fertiliser product per hectare, per acre and for the whole field, with bag count.

Category: Agriculture · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/fertilizer-application-rate-calculator

Fertiliser recommendations are given in nutrient; you buy product. Divide the nutrient rate by the product’s nutrient content to get the product rate.

Also called: Fertilizer rate calculator, Fertiliser product calculator.

## Inputs
- Nutrient rate (default 100)
- Rate unit (options: kg per hectare, kg per acre, lb per acre; default kg_ha)
- Nutrient content of the product (unit %; default 46)
- Field area (default 2)
- Area in (options: Acres, Hectares; default ha)
- Bag size (optional) (unit kg; default 45; optional)

## Results
- Product for the field
- Product per hectare
- Product per acre
- Product per acre (pounds)
- Nutrient applied to the field
- Bags to buy

## Formula

```
Product rate = Nutrient rate ÷ (Nutrient % ÷ 100);  Product for field = Product rate × Area
```

Where:
- Nutrient rate: kg or lb of nutrient per unit area
- Nutrient %: guaranteed analysis of the product

## Worked example
1. Product rate = 100 ÷ 0.46 = 217.39 kg/ha (87.98 kg/acre).
2. For 2 ha: 217.39 × 2 = 434.78 kg, or 10 bags of 45 kg (9.66 rounded up).

**Result:** 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.

## Related calculators
- [Fertiliser NPK Calculator](https://calculators.geekmidst.com/calculators/fertilizer-npk-blend-calculator)
- [Manure Application Rate Calculator](https://calculators.geekmidst.com/calculators/manure-application-rate-calculator)
- [Seed Rate Calculator](https://calculators.geekmidst.com/calculators/seed-quantity-per-acre-calculator)

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/fertilizer-application-rate-calculator