Fertilizer (NPK) Calculator

Stop guessing with your lawn. Calculate exactly how many pounds of fertilizer you need to reach your target nutrient levels.

N (Nitrogen)
P (Phosphorus)
K (Potassium)
Total Fertilizer Needed
25
Pounds

This covers 5,000 sq ft at 1.0 lb N rate.

What is N-P-K?

I genuinely believe that the "N-P-K" numbers on a fertilizer bag are the most important part of gardening. They represent the percentage (by weight) of Nitrogen, Phosphorus, and Potassium in the bag. A 20-0-10 bag is 20% Nitrogen. If you buy a 50lb bag, only 10lbs of it is actually nitrogen—the rest is filler and other nutrients.

The "Standard" Rate: Most lawn experts recommend applying 1 pound of Nitrogen per 1,000 square feet per application. Applying too much at once can "burn" the grass, and too little won't give you that lush green look.

Nutrient Guide:

  • Nitrogen (N): Promotes green, leafy growth (Up).
  • Phosphorus (P): Promotes root and flower development (Down).
  • Potassium (K): Promotes overall plant health and disease resistance (All around).