Fertilizer Ratio Converter
Convert NPK fertilizer ratios and calculate how much fertilizer to apply per area or per gallon.
Enter your fertilizer's NPK numbers and bag size to calculate nutrient content.
Fertilizer labels show an NPK ratio — three numbers representing the percentage of:
- N = Nitrogen (leaf/stem growth)
- P = Phosphorus (root/flower development)
- K = Potassium (overall plant health)
How to read NPK: A bag labeled 10-10-10 contains:
- 10% nitrogen, 10% phosphorus, 10% potassium
- The rest (70%) is filler/carrier material
Application calculation:
- Nutrient per bag = Bag weight × (% / 100)
- Example: 50 lb bag of 10-10-10 contains 5 lb of each nutrient
Common NPK ratios:
| Ratio | Best for |
|---|---|
| 10-10-10 | General purpose (balanced) |
| 20-5-10 | Lawns (high nitrogen) |
| 5-10-10 | Flowers and fruit |
| 0-20-0 | Root development (starter) |
| 15-0-15 | Winter lawn care |
Liquid fertilizer dilution:
- Rate is usually given as tablespoons per gallon or mL per liter
- 1 tablespoon = 14.79 mL
- 1 US gallon = 3.785 liters