Lawn Fertilizer Calculator: Determine the Right Amount for a Healthy Lawn

Lawn fertilizers are primarily composed of nitrogen, with smaller amounts of phosphorus and potassium. The three numbers on a fertilizer bag (such as 30-2-3) represent the percentage of each nutrient by weight. The first number—typically between 25 and 35—indicates the nitrogen content, which is the most critical nutrient for vigorous grass growth.

Use the calculator below to determine how many pounds of fertilizer your lawn needs annually. In most cases, you'll apply one-half to one-third of this total in two or three well-spaced applications during the growing season.

Lawn Fertilizer Calculator

Enter the requested information below, then click Calculate to see the range of fertilizer amounts needed per year. Remember, applying too much fertilizer can be just as damaging as applying too little.

Square feet to be fertilized Percent nitrogen in the fertilizer Type of grass (check one)
Fescue Kentucky Bluegrass, Ryegrass Bermuda Bahi St. Augustine Pounds of fertilizer needed per year:
    to

Please note: For your convenience, this calculation has been rounded up slightly.

Important reminder: Every effort has been made to ensure the accuracy of this calculation. But before purchasing materials for any project, please check amounts with your suppliers or contractors.

Helpful Tips

• Fertilizer bags always provide a recommended application rate. This calculator will also give you the details you need.
• Most lawns need regular feeding—once or twice a year—to stay lush and healthy. Feed cool-season grasses (which generally stay green year-round and grow primarily in the South) in spring and autumn; feed warm-season grasses (Northern grasses that go dormant in fall and winter) in spring and summer.
• Apply fertilizer with a spreader for even distribution. Since a lawn's greatest need is nitrogen, the amount of fertilizer required depends on the nitrogen content of the product you choose.