NPK Calculator
Estimate how much N-P-K analysis a fertilizer application supplies at a selected product rate.
Results
Fertilizer product
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Nitrogen (N)
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Phosphate (P₂O₅)
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Potash (K₂O)
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Use the result as a planning estimate and verify project-specific measurements, product information and site conditions where relevant.
How it works
The calculator first finds total fertilizer product applied, then multiplies by each labeled N-P-K percentage.
nutrient amount = product mass × label percentageWorked example
Applying 4 lb of 10-10-10 fertilizer supplies 0.4 lb each of labeled N, P₂O₅ and K₂O.
Assumptions
- The second and third fertilizer-analysis numbers are conventionally expressed as P₂O₅ and K₂O, not elemental phosphorus and potassium.
Limitations
- This calculator does not determine an agronomic fertilizer recommendation; use soil tests, label directions and local guidance where appropriate.