Fertilizer (NPK) calculator

Enter the N-P-K numbers from the bag, your area and the nitrogen amount you want to apply. You get the product amount and the N, P₂O₅ and K₂O it delivers.

N (nitrogen) %P (as P₂O₅) %K (as K₂O) %AreaNitrogen to apply

Product to spread—

Nutrients delivered—

⚠️ This tool does not recommend a dose. Follow the instructions on the label and, if you can, a soil test.

How is it calculated?

Product = nitrogen amount × area ÷ (N% ÷ 100). The same product amount × P% and × K% gives the phosphate (P₂O₅) and potash (K₂O) delivered. Example: 1 lb of N per 1,000 sq ft from a 10-10-10 fertilizer means 10 lb of product.

Sources

How to Calculate Fertilizer Rates for the Lawn — Iowa State University Extension

Other tools

Planting calendarWhen to sow, when to harvest Soil & mulchHow many bags, how many cubic yards Plant spacingHow many plants fit WateringWeekly water for your area Grass seedPounds per area