Enter the first number on the bag (the N in N-P-K), your lawn size and the nitrogen rate, and get pounds of product.
By the nitrogen percentage on the bag and the nitrogen rate you want: rate ÷ nitrogen as a decimal, the method Purdue and Iowa State use.
| Bag nitrogen | ¼ lb N | ½ lb N | ¾ lb N | 1 lb N |
|---|---|---|---|---|
| 10% | 2.5 lb | 5.0 lb | 7.5 lb | 10.0 lb |
| 16% | 1.6 lb | 3.1 lb | 4.7 lb | 6.3 lb |
| 20% | 1.3 lb | 2.5 lb | 3.8 lb | 5.0 lb |
| 24% | 1.0 lb | 2.1 lb | 3.1 lb | 4.2 lb |
| 29% | 0.9 lb | 1.7 lb | 2.6 lb | 3.4 lb |
| 32% | 0.8 lb | 1.6 lb | 2.3 lb | 3.1 lb |
| 46% | 0.5 lb | 1.1 lb | 1.6 lb | 2.2 lb |
Pounds of nitrogen per 1,000 sq ft per year, from UGA Extension. Split the yearly amount into several smaller feedings rather than one large one.
| Grass | Nitrogen per year | Notes |
|---|---|---|
| Centipedegrass | 1 to 2 lb | The lower end is usually enough |
| Zoysiagrass | 1 to 2 lb | |
| St. Augustinegrass | 2 to 5 lb | Lower end in middle and north Georgia, higher in the south |
| Bermudagrass | 2 to 4 lb | For example, four feedings of 1 lb |
Divide the nitrogen rate you want by the bag’s nitrogen as a decimal to get pounds per 1,000 sq ft, then multiply by your lawn size in thousands of square feet. Purdue’s example: 0.75 lb of nitrogen from a 16-8-8 bag is 4.69 lb per 1,000 sq ft, or about 37 lb on an 8,000 sq ft lawn.
The first one. A 16-8-8 bag is 16% nitrogen, which the formula uses as 0.16, the way Purdue and Iowa State do.
Iowa State Extension’s quick table covers ¼ to 1 lb of nitrogen per 1,000 sq ft per application, and Purdue’s worked example uses ¾ lb. Your state Extension’s lawn calendar gives the right rate and timing for your grass.
Iowa State Extension’s schedule is spring (April or May), mid-September and late October or early November. A high-quality lawn gets all three, a moderate program the two fall feedings, and a low-maintenance lawn just the late fall one. It says not to fertilize cool-season grass in June, July or August.
Purdue Extension recommends 0.75 to 1 lb of nitrogen per 1,000 sq ft four to six weeks after the seed comes up, and again at eight to ten weeks. For a mid-August seeding, that’s mid to late September and mid to late October.
Yes. K-State Research and Extension suggests 1 to 1.5 lb of quick-release nitrogen per 1,000 sq ft in September and 1 lb in November for Kansas lawns, while Iowa State’s range per application is 0.5 to 1 lb. Use your own state Extension’s schedule.
UGA Extension says to wait until the soil 4 inches down is at or above 65°F and the grass is actively growing. Fed earlier, roots take up little of the nitrate and more of it can leach away. In North and Central Florida, UF/IFAS says lawns grow from about April through September, so fertilize only then; South Florida lawns grow year-round.
UGA Extension puts centipedegrass and zoysiagrass at 1 to 2 lb of nitrogen per 1,000 sq ft a year, St. Augustinegrass at 2 to 5 lb (the lower end in middle and north Georgia) and Bermudagrass at 2 to 4 lb. Spread it over several feedings: UGA’s example is four 1 lb feedings for Bermuda rather than one 4 lb feeding.
UF/IFAS says no more than 1 lb of nitrogen per 1,000 sq ft per application, whatever the grass, and to choose a fertilizer whose nitrogen is mostly slow-release. UF/IFAS also notes that local fertilizer ordinances can rule out summer feeding in some places, so check with your county Extension office.
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Results are estimates. Suppliers’ bag sizes, pallet sizes and stone weights vary, so check theirs before you order.
Mix 10 or more small soil cores from your lawn, send about 2 cups to your state's extension lab, and add lime only if the report says your pH is too low, in spring or fall, at no more than 50 lb per 1,000 sq ft at a time.
October 12, 2026
Weed and feed can kill broadleaf weeds like dandelions and clover while it fertilizes, but only on damp, actively growing weeds. For most cool-season lawns, early fall is the best time to apply it.
September 26, 2026
Fertilize cool-season grass mainly in fall (September through November), with an optional light feeding in late spring. Fertilize warm-season grass from late spring through summer, once it has fully greened up and the soil is about 65°F.
August 22, 2026
