Fertilizer Rate Calculator
Soil tests give nutrient needs in pounds of N, P2O5, K2O per acre — but you buy fertilizer by the bag. This converts the recommendation into product pounds and cost.
Formula (Cropaia/NRCS): fertilizer product needed (lb/acre) = nutrient rate (lb/acre) × 100 ÷ % nutrient in the fertilizer. Example: 50 lb N/acre with urea 46-0-0 = 50 × 100 ÷ 46 = 108.7 lb product/acre. Read the grade as N-P2O5-K2O: for phosphorus use the second number, potassium the third. Cost: total pounds ÷ 2000 = tons; tons × price per ton = cost. Caution: follow soil-test recommendations and local nutrient-management rules — over-application wastes money and pollutes water.
FAQ
How do I convert a nutrient rate to product?
Divide the desired pounds of nutrient per acre by the nutrient percentage in the fertilizer (as a decimal), i.e., rate × 100 ÷ grade %. Urea 46% N: 50 lb N ÷ 0.46 = 108.7 lb of urea.
What do the three numbers on fertilizer mean?
They're the guaranteed N-P2O5-K2O percentages: nitrogen, phosphate, and potash. 46-0-0 is straight nitrogen (urea); 12-61-0 is MAP (mostly phosphate). Use the number matching the nutrient your soil test calls for.
How much does fertilizer cost per acre?
In 2026 examples, urea runs roughly $350-$550/ton, so 50 lb of N costs about $40-$65 per acre depending on the N price. Use your actual delivered price.
Figures are editable example defaults for planning, not guarantees. Crop inputs, prices, and moisture handling vary by farm, region, and year — verify with your local extension service and agronomist.