Fertilizer rate & the NPK math
Fertilizer is dosed by pounds of nitrogen (N) per 1,000 sq ft, not pounds of product. The first number in the NPK on the bag is the %N. To put down 1 lb of N you need 100 ÷ %N pounds of product per 1,000 sq ft. A typical application is about 1 lb of N per 1,000 sq ft. Use this in the fertilizer calculator.
| Product %N (first NPK number) | lb of product per 1,000 sq ft at 1 lb N |
|---|---|
| 10% N | 10.00 lb |
| 15% N | 6.67 lb |
| 20% N | 5.00 lb |
| 26% N | 3.85 lb |
| 30% N | 3.33 lb |
| 46% N | 2.17 lb |
lb of product = (lb N wanted) ÷ (%N ÷ 100). A typical application is ~1 lb of N per 1,000 sq ft. Labeled planning math — follow the product label and a soil test.