Lawn Fertilizer Calculator — How Much Fertilizer Do You Need?
Enter your lawn size, the nitrogen rate you want, and your fertilizer’s first NPK number (its nitrogen %) to get how many pounds and bags of product you need.
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How it works
lb nitrogen = (area ÷ 1,000) × N rate; lb product = lb nitrogen × 100 ÷ %N; bags = ceil(lb product ÷ bag size)
Fertilizer by lawn size (1 lb nitrogen per 1,000 sq ft)
| Lawn size | Nitrogen | Product @ 25% N | Product @ 10% N |
|---|---|---|---|
| 1,000 sq ft | 1 lb | 4 lb | 10 lb |
| 2,500 sq ft | 2.5 lb | 10 lb | 25 lb |
| 5,000 sq ft | 5 lb | 20 lb | 50 lb |
| 7,500 sq ft | 7.5 lb | 30 lb | 75 lb |
| 10,000 sq ft | 10 lb | 40 lb | 100 lb |
At the standard 1 lb of actual nitrogen per 1,000 sq ft per application. “Product” is pounds of bagged fertilizer — divide the nitrogen by the bag’s first number (the % N). A 25-0-10 bag is 25% N; a 10-10-10 is 10% N.
Frequently asked questions
How much fertilizer do I need per 1,000 sq ft?
Apply about 1 lb of actual nitrogen per 1,000 sq ft per feeding, then divide by the bag’s first number (% N). A 25-0-10 fertilizer (25% N) needs 4 lb of product per 1,000 sq ft; a 10-10-10 needs 10 lb.
How do I convert the NPK number to pounds of fertilizer?
The first NPK number is the percent nitrogen by weight. Pounds of product = pounds of nitrogen ÷ (%N ÷ 100). To get 1 lb of nitrogen from a 20% fertilizer: 1 ÷ 0.20 = 5 lb of product.
How much fertilizer for a 5,000 sq ft lawn?
At 1 lb N per 1,000 sq ft, a 5,000 sq ft lawn needs 5 lb of actual nitrogen — about 20 lb of a 25% N fertilizer or 50 lb of a 10% N product. Do not exceed roughly 1 lb of nitrogen per 1,000 sq ft in a single application.