Lawn fertilizer calculator
How many pounds of fertilizer to spread for a given amount of nitrogen, and how many bags your lawn needs.
Fertilizer to spread
- Bags
- One bag covers
How to use it
Enter your lawn's area in square feet, the nitrogen percentage from the bag (the first of the three numbers, so 26 for a 26-5-10 bag), how much nitrogen you want to apply per 1,000 sq ft, and the bag weight. The calculator shows how many pounds of product to spread, how many bags to buy, and how much lawn one bag covers.
Lawn fertilizer recommendations are given in pounds of nitrogen per 1,000 sq ft, not pounds of product. 1 lb of nitrogen per 1,000 sq ft per application is a common rate; your soil test or local extension office can tell you what your lawn needs.
How it's calculated
This is the method university extension services teach:
- Pounds of product per 1,000 sq ft = pounds of nitrogen wanted ÷ (nitrogen % ÷ 100).
- Total pounds = pounds per 1,000 × (lawn area ÷ 1,000).
- Bags = total pounds ÷ bag weight, rounded up.
| Bag | To apply 1 lb N per 1,000 sq ft | One 50 lb bag covers |
|---|---|---|
| 10-10-10 | 10 lb per 1,000 sq ft | 5,000 sq ft |
| 16-4-8 | 6.25 lb per 1,000 sq ft | 8,000 sq ft |
| 21-0-0 | 4.76 lb per 1,000 sq ft | 10,500 sq ft |
| 26-5-10 | 3.85 lb per 1,000 sq ft | 13,000 sq ft |
| 32-0-4 | 3.13 lb per 1,000 sq ft | 16,000 sq ft |
Tips
- Don't overdo it. Extension services generally advise no more than 1 lb of quick-release nitrogen per 1,000 sq ft in one application. Too much burns grass and washes into waterways.
- Check your state's rules. Several states limit how much nitrogen and phosphorus you can apply, and when.
- Calibrate your spreader with the bag's setting chart, and spread half the amount in one direction and half crosswise for even coverage.
- Get a soil test every few years. It tells you whether your lawn needs phosphorus or potassium at all.