Calculator
Plotly Graph
Example graph based on 20% nitrogen in 10 L water.
Example Data Table
| Scenario | Fertilizer | N % | Water Volume | Estimated Nitrogen ppm |
|---|---|---|---|---|
| Gentle seedling feed | 2 g | 20% | 10 L | 40 ppm |
| Moderate garden feed | 5 g | 20% | 10 L | 100 ppm |
| Strong vegetative feed | 7.5 g | 20% | 10 L | 150 ppm |
| Stock injector output | 600 g in stock tank | 20% | 10 L stock, 1:100 | 120 ppm output |
Formula Used
1) Nitrogen ppm from fertilizer amount
ppm = (Fertilizer grams × Nitrogen fraction × Purity fraction × 1000) ÷ Final liters
Because 1 gram equals 1000 milligrams, and ppm in water is effectively milligrams per liter.
2) Fertilizer amount from target ppm
Required fertilizer grams = (Target ppm × Final liters) ÷ (1000 × Nitrogen fraction × Purity fraction)
Use this reverse formula when you already know the nitrogen ppm you want to apply.
3) Stock tank with injector ratio
Required stock grams = (Target output ppm × Injector ratio × Stock liters) ÷ (1000 × Nitrogen fraction × Purity fraction)
A 1:100 injector means the stock tank concentration must be 100 times stronger than the final output concentration.
How to Use This Calculator
- Select the calculation mode that fits your task.
- Enter the fertilizer label nitrogen percentage as total N.
- Enter purity if the product is not fully usable material.
- For direct mode, input fertilizer mass and final water volume.
- For reverse mode, input the target nitrogen ppm and water volume.
- For injector systems, enter stock volume and the ratio as
1:X. - Press the calculate button.
- Read the result card above the form, then export CSV or PDF if needed.
Frequently Asked Questions
1) What does nitrogen ppm mean in gardening?
Nitrogen ppm means parts per million of nitrogen in the final water solution. In water-based feeding, it is effectively the same as milligrams of nitrogen per liter.
2) Should I use the first number on a fertilizer label?
Yes. For most common labels like 20-20-20, the first number is total nitrogen. Enter that value as the nitrogen percentage for this calculator.
3) Why is purity included?
Purity helps when the material is not fully active product. If the fertilizer is fully usable, keep purity at 100%.
4) Is ppm the same as EC?
No. ppm here is calculated nitrogen only. EC measures total dissolved salts from all nutrients, not just nitrogen.
5) How do I use the stock tank mode?
Enter the desired output ppm, stock tank volume, and injector ratio. The calculator determines how much fertilizer to place in the stock tank.
6) Can I use gallons instead of liters?
Yes. The calculator supports liters, milliliters, US gallons, UK gallons, and cubic meters. It converts everything internally to liters.
7) What nitrogen ppm is too high?
That depends on crop type, growth stage, root zone, and irrigation frequency. Always compare your result with crop-specific guidance before feeding heavily.
8) Why does the result appear above the form?
It keeps the answer immediately visible after submission. You can review the result, export it, and then adjust values without scrolling upward again.