Fertiliser Product Calculator
Work out how much product supplies the nutrient rate you want, from the percentage on the label.
Part of the 🌾 Farmers toolkit, with more tools made for the job.
Product 1
Product 2 (optional)
Product 3 (optional)
Use one row for each product. The percentage is on the label, for example 46 for urea’s nitrogen.
Type the area and, for one product, the nutrient you want and the percentage on the label. The amount to buy appears here.
This works out how much product supplies the nutrient rate you choose. It does not say what rate to use. That depends on your crop, soil and local advice.
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Fertiliser is bought by the bag, but rates are given as nutrient. Type the nutrient you want per hectare or acre and the percentage the product contains, and this shows how much product that is, in total and in cost.
A product that is 46% nitrogen is only 46% nitrogen by weight, so to put on 120 kg of nitrogen you need about 261 kg of the product. Dividing by the percentage is the step people most often skip.
How it’s worked out
- Product needed per area is the nutrient rate divided by the nutrient percentage, as a fraction of 1.
- Total product is that times the area.
- Cost is the total product, in tonnes (or tons of 2,000 lb), times the price per tonne.
To apply 120 kg of nitrogen per hectare from urea that is 46% nitrogen, you need 120 divided by 0.46, about 261 kg of urea per hectare. Over 10 hectares that is 2,609 kg.
Common mistakes
- Buying the nutrient number as if it were the product weight. 120 kg of nitrogen is not 120 kg of fertiliser.
- Forgetting that blends supply several nutrients. If one product gives two nutrients, work out the amount for the nutrient you are matching and check the other.
- Mixing kilograms per hectare with pounds per acre.
- Comparing prices per bag with different bag sizes. Use price per tonne.
Questions
Is my recommendation in nutrient or in product?
Soil test recommendations are normally given as pounds or kilograms of the nutrient itself (N, P₂O₅ or K₂O), not as fertiliser product. Type the nutrient amount here. If your recommendation is already in product, you do not need this step.
Where do I find the percentage?
On the bag or the supplier's sheet, for example 46-0-0 for urea, which means 46% nitrogen. Phosphate and potash are given as P₂O₅ and K₂O.
Does it tell me what rate to apply?
No. The right rate depends on the crop, soil tests and local advice. This only converts the rate you choose into product.
Can I add more than one product?
Yes. There are three rows. Add the amounts in each row to see the total product and cost.
Where the method comes from
Estimates only
These are estimates and general information, not agronomic, financial or professional advice. Rates, timings and costs depend on your crop, land, weather and local rules.
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