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Fertiliser calculator

How many bags, how many spreader loads - and how much nitrogen, phosphorus, potassium and sulphur actually goes on? Enter your rate, the area and the analysis on the bag.

The job

How much product you spread a hectare.

Hectares to spread. 1 acre = 0.405 ha.

1,000 for a 1-tonne bulka bag, or 25, 40, 50…

What the spreader holds. 0 to skip.

Optional: what you pay a tonne. 0 to skip costs.

The analysis on the bag
How does your label show phosphorus and potassium?

Nitrogen

Phosphorus

Potassium

Sulphur

The example is 10-22-0-1.5 - use the numbers printed on your own bag or delivery docket.

For this paddock

4 t4,000 kg of product
44 bags of 1 t
1spreader loads

What’s in every 100 kg of product

  • N 10 kg
  • P 22 kg
  • K 0 kg
  • S 1.5 kg
  • Other 66.5 kg
Nitrogen (N)
10 kg/ha · 400 kg in all
Phosphorus (P)
22 kg/ha · 880 kg in all (50 kg/ha as P₂O₅)
Potassium (K)
0 kg/ha · 0 kg in all (0 kg/ha as K₂O)
Sulphur (S)
1.5 kg/ha · 60 kg in all
Rate in lb per acre
89.2 lb/ac
Spreader loads
1 full load
Cost per hectare
Enter your price
Cost for the paddock
Enter your price
Link to these numbers

How we work it out

  • Product: rate × area. Bags and spreader loads = product ÷ bag or bin size (rounded up to buy).
  • Nutrients: rate × the label %. So 100 kg/ha of a 10% N product puts on 10 kg of N a hectare.
  • P and K: P = P₂O₅ × 0.436 and K = K₂O × 0.830 - the standard factors, so labels from any country compare fairly.

This does the arithmetic only - it doesn’t tell you what or how much to spread. A soil or plant test and your agronomist are the best guide to rates. We don’t show fertiliser prices; use what you pay. Nothing you type is stored or sent anywhere. For kg/ha ↔ lb/acre and other units use the farm unit converter.

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