How do you calculate pounds of nitrogen per 1,000 sq ft?
Divide 100 by the first number on the bag. A 24-0-4 product needs 4.17 lb of product per 1,000 ft² to deliver 1 lb of actual nitrogen; a 10-10-10 needs 10 lb.
The formula is lb of product = target lb N × 100 ÷ N%. One pound of actual nitrogen per 1,000 ft² is the standard single application, and you should never exceed it in one pass from a quick-release product.
This is why the coverage claim on the front of the bag is worth checking. A 15 lb bag of 24-0-4 carries 3.6 lb of nitrogen, which covers 3,600 ft² at the standard rate — not the 5,000 ft² the bag may advertise.
| Analysis | Nitrogen | lb product per 1,000 ft² | A 15 lb bag covers |
|---|---|---|---|
| 24-0-4 | 24% | 4.17 lb | 3,600 ft² |
| 29-0-4 | 29% | 3.45 lb | 4,350 ft² |
| 32-0-4 | 32% | 3.13 lb | 4,800 ft² |
| 20-20-20 | 20% | 5.00 lb | 3,000 ft² |
| 16-4-8 | 16% | 6.25 lb | 2,400 ft² |
| 10-10-10 | 10% | 10.00 lb | 1,500 ft² |
| 12-4-8 | 12% | 8.33 lb | 1,800 ft² |
| 5-10-5 | 5% | 20.00 lb | 750 ft² |
Reading the chart
The rule is one line of arithmetic: 100 divided by the first number on the bag gives the pounds of product per 1,000 ft² for 1 lb of actual nitrogen.
That is why the "covers up to 5,000 sq ft" claim on the front of the bag is worth checking rather than trusting. A 15 lb bag of 24-0-4 delivers 3.6 lb of nitrogen, which at the standard rate covers 3,600 ft² — not 5,000. Manufacturers are often quoting a lighter rate than 1 lb N.
| Lawn type | Nitrogen per year | Applications |
|---|---|---|
| Cool-season, low maintenance | 1-2 lb | 1-2 applications |
| Cool-season, standard | 2-4 lb | 3-4 applications |
| Warm-season, standard | 2-4 lb | 3-4 applications |
| Bermudagrass, high maintenance | 4-6 lb | 4-6 applications |
| Centipede (low feeder) | 0.5-1 lb | 1 application |
Splitting the annual budget
Never apply more than 1 lb of nitrogen per 1,000 ft² at once from a quick-release product. To reach a 4 lb annual budget you make four applications spread through the growing season, not one heavy one.
Timing follows the grass. For cool-season lawns the two most valuable applications are in autumn — early and late — because that is when the grass is building roots and carbohydrate reserves. For warm-season lawns, feed through the summer growth period and stop 4-6 weeks before the first expected frost, since pushing growth into dormancy invites winter damage.
Slow-release nitrogen changes the arithmetic: it can go down heavier because it releases over weeks, and the label will say so. Read it.
Common questions
How do I calculate pounds of fertilizer per 1,000 square feet?
Divide 100 by the first number on the bag. A 32-0-4 needs 3.13 lb of product per 1,000 ft² to deliver 1 lb of actual nitrogen.
How much nitrogen does a lawn need per year?
2-4 lb per 1,000 ft² for most lawns at standard maintenance, split across three or four applications. Centipede wants 0.5-1 lb; high-maintenance bermuda can take 4-6.
Is the coverage claim on the bag accurate?
Often optimistic. A 15 lb bag of 24-0-4 carries 3.6 lb of nitrogen, which covers 3,600 ft² at the standard 1 lb rate — not the 5,000 ft² the bag may claim. Work it out from the analysis.