🧪 Fertilizer Calculator
Calculate NPK fertilizer requirements for optimal lawn nutrition and healthy growth
Privacy First: All calculations happen in your browser. No data is sent to any server.
Calculate Fertilizer Amount
Enter the NPK ratio from your fertilizer bag (e.g., 24-4-12)
Recommended: 0.5-1.0 lbs per application (never exceed 1.5 lbs)
How to Use This Calculator
- Calculate your lawn square footage (length × width)
- Find the NPK numbers on your fertilizer bag (e.g., 24-4-12)
- Enter each NPK percentage in the corresponding field
- Set your desired nitrogen rate (0.5-1.0 lbs per 1000 sq ft is typical)
- Click "Calculate" to see how many pounds of fertilizer you need
- Apply evenly across your lawn and water immediately
Frequently Asked Questions
What do the NPK numbers mean?
NPK stands for Nitrogen (N), Phosphorus (P), and Potassium (K). The numbers represent the percentage by weight of each nutrient. A 24-4-12 fertilizer contains 24% nitrogen, 4% phosphorus, and 12% potassium.
How much nitrogen should I apply to my lawn?
Most lawns benefit from 0.5-1.0 pounds of nitrogen per 1000 square feet per application. Avoid applying more than 1 lb nitrogen at once to prevent burning.
How often should I fertilize my lawn?
Cool-season grasses should be fertilized 2-4 times per year. Warm-season grasses need 2-3 applications during the growing season. Split the total annual nitrogen into these applications.
Can I apply too much fertilizer?
Yes, over-fertilizing can burn your lawn, promote excessive growth, and contaminate groundwater. Always follow recommended rates and water immediately after application.