Lawn fertilizer is rated by nutrients, not by how many bags cover your yard, so the trick is turning a target nutrient rate into pounds of the specific product in front of you. It is easier than it looks.
Start with your lawn's square footage
Every rate is "per 1,000 square feet," so measure length × width (add up rectangles for odd shapes) and keep that number handy. The fertilizer calculator turns it into pounds for you.
The one-pound-of-nitrogen rule
The standard guideline is about 1 pound of nitrogen per 1,000 sq ft per feeding, with most lawns getting 2–4 pounds of nitrogen per 1,000 sq ft across a whole year. Nitrogen — the first N-P-K number — is what drives green growth.
Read the three N-P-K numbers
Every bag lists three numbers, like 26-0-3. They are the percentages of Nitrogen, Phosphorus, and Potassium by weight, so a 26-0-3 bag is 26% nitrogen — 26 pounds of N in every 100 pounds of product.
Turn it into pounds of product
To deliver 1 lb of nitrogen, divide 100 by the first number: 100 ÷ 26 ≈ 3.8 lb of product per 1,000 sq ft. For a 5,000 sq ft lawn that is about 19 lb of that fertilizer per feeding. A higher first number means you spread less product.
A few tips
- Never exceed the label rate — too much nitrogen burns the lawn and runs off into waterways.
- Slow-release nitrogen feeds longer and burns less than quick-release.
- Water it in after applying, and calibrate your spreader so you are not guessing.
Enter your lawn size and the bag's analysis in the fertilizer calculator, and pair it with the grass seed calculator when you are seeding.