Fertiliser rate calculator
How much product to apply to hit a target kg/ha of N, P or K, and what it costs.
South African bags and recommendations use elemental P and K. Most other countries print P₂O₅ and K₂O.
From your soil test recommendation.
Blend ratios are N:P:K. Presets are converted for you whichever label form you choose above.
Any currency; the cost comes out in the same one.
How this is calculated
Product rate = target nutrient ÷ nutrient content. For example, 60 kg N/ha from LAN at 28% N is 60 ÷ 0.28 = 214 kg of LAN per hectare. Multiply by your hectares for the total, and divide by 50 kg and round up for bags, because you cannot buy part of a bag.
Blends supply more than one nutrient. The rate is set by the nutrient you target, and the others come along as a by-product: 91 kg/ha of MAP (11:22:0) for 20 kg P also gives 10 kg N, which you can subtract from your nitrogen top-dressing.
P and K can be written two ways. South Africa labels them as the elements; most other countries print the oxides. The conversions are P = P₂O₅ × 0.4364 and K = K₂O × 0.8301, so DAP labelled 18:46:0 is 18:20:0 in elemental terms. Keep your recommendation and your label in the same form, and this calculator converts for you.
Read the guide: From soil test to fertiliser rate: working out what to apply
Results are estimates for planning. Check product labels and local recommendations before you apply anything.