Calculator · nutrition
Nutrient rate converter
Convert between a product rate and the nutrient rate it supplies, and between metric and US areal units.
Result
Enter values to see a result.
Formula & assumptions
Nutrient rate from product rate and grade
formula v1.0.0 · calc v1 · reviewed 2026-08-27nutrient_kg_per_ha = product_kg_per_ha × grade% ÷ 100
Applies to: Converting between a rate of product and the nutrient it supplies, where the reader supplies both the rate and the grade.
Assumptions
- The grade is the declared percentage of that nutrient in the product as sold.
Limitations
- This is arithmetic on a rate the reader provides. It is not a recommendation, and it does not say what rate is appropriate — that depends on soil test, crop, season and local regulation.
- Grades for phosphorus and potassium are conventionally expressed as P₂O₅ and K₂O, not as elemental P and K. Converting between the oxide and the element is a separate step.
Sources: International Fertilizer Association (IFA) (opens in a new tab), Penn State Extension, The Pennsylvania State University (opens in a new tab)
Product rate for a nutrient rate
formula v1.0.0 · calc v1 · reviewed 2026-08-27product_kg_per_ha = nutrient_kg_per_ha ÷ (grade% ÷ 100)
Applies to: Converting a nutrient rate the reader has decided on into the product rate that supplies it.
Assumptions
- The grade is the declared percentage of that nutrient in the product as sold.
Limitations
- The nutrient rate must come from a soil test, a plan or a regulation. This converts it; it does not choose it.
- A product rate derived this way ignores every other nutrient in a compound fertiliser.
Sources: International Fertilizer Association (IFA) (opens in a new tab), Penn State Extension, The Pennsylvania State University (opens in a new tab)
Yield: kg/ha → lb/acre
formula v1.0.0 · calc v1 · reviewed 2026-07-16lb/acre = kg/ha ÷ 0.45359237 ÷ (10000 ÷ 4046.8564224) [exact by definition]
Applies to: Any yield expressed per unit area.
Assumptions
- The pound (0.45359237 kg) and the acre (4046.8564224 m²) are exactly defined, so the factor is exact rather than measured.
Limitations
- A unit conversion. It carries no commodity dependence and no bushel convention.
About this tool
- This converts a rate the reader supplies. It does not decide what rate is appropriate — that comes from a soil test, a nutrient plan and local regulation, none of which this tool can see.
- Phosphorus and potassium grades are conventionally declared as P₂O₅ and K₂O rather than elemental P and K. Converting oxide to element is a separate step, in the fertilizer nutrient calculator.
- A compound fertiliser supplies several nutrients at once; matching one of them will over- or under-supply the others.
Educational reference — not a prescription
This is unit arithmetic on a rate you provide, not a fertiliser recommendation. Nutrient application is regulated in many jurisdictions and must follow the applicable nutrient management rules.
- These calculators are for education and reference. The quality of any result depends entirely on the accuracy of the values you enter.
- Local agronomic conditions, legal requirements, product labels, and professional advice may override a general calculation.
- Results are not pesticide, fertilizer, irrigation, or veterinary prescriptions, and are not a substitute for advice from a qualified agronomist or your local extension service.