NPK Calculator - What Am I Applying?
Already applied fertilizer or about to? Enter the details to see exactly how much nitrogen, phosphorus, and potassium your lawn or garden is receiving.
Reverse NPK Calculator
The 3 numbers on the bag (e.g. 10-10-10)
Total weight of fertilizer you spread
Size of your lawn or garden bed
How to Use This Calculator
Enter the NPK numbers from your fertilizer bag (the 3 numbers separated by dashes), the total weight of product you applied, and the area you covered. The calculator shows how much of each nutrient reaches each 1,000 square feet (or 100 m²) of your lawn or garden.
Most lawns need about 1 pound of nitrogen per 1,000 square feet per application. If the calculator shows more than 1.5 lbs N, you may be over-applying. Use the Fix My Mistake tool for remediation steps.