What do N, P, and K mean on a fertilizer label?

N is nitrogen (promotes leafy growth), P is phosphorus expressed as P₂O₅ (supports roots and flowering), and K is potassium expressed as K₂O (improves overall plant health and disease resistance).

Why does this calculator use P₂O₅ instead of elemental phosphorus?

Commercial fertilizer labels report phosphorus as P₂O₅ (phosphorus pentoxide), which is the industry standard. To convert to elemental P, multiply the P₂O₅ value by 0.436.

How much fertilizer do I need for 100 m²?

It depends on the fertilizer type and NPK ratio. For example, Urea (46-0-0) requires about 0.65 kg per 100 m² to supply the recommended nitrogen dose. Use this calculator to get an exact figure for your specific fertilizer.

Can I use this calculator for any fertilizer brand?

Yes. Select Custom and enter the N, P₂O₅, and K₂O percentages printed on your fertilizer bag. The calculator will compute the required amount based on standard nutrient application rates.

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Fertilizer Calculator

P values represent P₂O₅ (phosphorus pentoxide) — the industry standard on fertilizer labels.

Fertilizer Type

N: 46% | P₂O₅: 0% | K₂O: 0%

Area (m²)