Fertilizer Calculator
Convert an agronomic nutrient recommendation into fertilizer product quantity, bags and optional purchasing cost.
Fertilizer product calculator
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Fertilizer calculation formula
Fertilizer product rate = actual nutrient needed ÷ nutrient fraction in the product. For example, if a recommendation calls for 60 lb of nitrogen per acre and the fertilizer is 46% nitrogen, the product rate is about 130.43 lb/acre.
University of Minnesota Extension uses the same core method: divide the required amount of actual nutrient by the nutrient fraction shown on the fertilizer label. Fertilizer labels state nutrient concentration as a percentage, such as 46-0-0 or 10-26-26.
Source: University of Minnesota Extension — Interpreting soil tests and fertilizer rates.
Frequently asked questions
How do I calculate fertilizer product rate?
Divide the required actual nutrient rate by the nutrient percentage expressed as a decimal. For 60 lb of nutrient with a 46% product, divide 60 by 0.46.
What does 46-0-0 mean?
It indicates 46% nitrogen by weight and no labeled phosphate or potash in that analysis.
Does this calculator recommend N, P or K rates?
No. It only converts a nutrient recommendation you already have into a fertilizer product amount.
Can I calculate bags and cost?
Yes. Enter bag weight and optional cost per bag to estimate exact bags, whole bags to purchase and total bag cost.