How It Works
This calculator works in 4 steps.
Enter the nutrient percent
Type the label percent of N, P₂O₅, or K₂O.
Enter the target ppm
Type the ppm of that nutrient the feeding plan calls for.
Enter volume or injector ratio
Type the water volume, or the injector ratio and stock tank size.
Read the product amount
The calculator returns grams per liter, oz per 100 gal, and stock tank amounts.
The Formula
The formula multiplies grams of product per liter by the nutrient percent and by 10 to give ppm.
ppm = (g/L) × %nutrient × 10ppm = (oz/100 gal) × %nutrient × 0.75Stock g/L = (g/L at target) × injector ratio- g/L:
- Product grams per liter of water
- %nutrient:
- Label percent of the nutrient
- oz/100 gal:
- Product ounces per 100 US gallons
200 ppm N from 20-20-20 needs 200 / (20 × 10) = 1 g/L, or 200 / (20 × 0.75) = 13.3 oz per 100 gallons.
Conversion Table
The conversion table converts 6 product rates into ppm nutrient and the US oz-per-100-gallon rate.
| Product rate | Nutrient | Nutrient ppm | US rate |
|---|---|---|---|
| 1 g/L | 20% N | 200 ppm N | 13.33 oz/100 gal |
| 0.5 g/L | 20% N | 100 ppm N | 6.667 oz/100 gal |
| 1 g/L | 15% N | 150 ppm N | 13.33 oz/100 gal |
| 0.75 g/L | 10% N | 75 ppm N | 10 oz/100 gal |
| 2 g/L | 12% N | 240 ppm N | 26.67 oz/100 gal |
| 1.25 g/L | 24% N | 300 ppm N | 16.67 oz/100 gal |
What Is the Fertilizer Dilution Calculator?
The Fertilizer Dilution Calculator is a tool that returns the amount of water-soluble or liquid fertilizer needed for a target nutrient concentration in ppm, using the nutrient percent on the product label. A 20-20-20 fertilizer at 1 g per liter delivers 200 ppm nitrogen.
Fertilizer labels list the guaranteed analysis as percent nitrogen (N), phosphate (P₂O₅), and potash (K₂O). The calculator works with any of the 3 and with injector ratios, such as 1:100. US growers often use the rule that 1 oz of product per 100 gallons supplies about 75 ppm of product, multiplied by the nutrient fraction.
Common Uses
There are 5 main uses of this calculator.
Greenhouse feeding
Growers set constant-feed ppm N.
Nursery production
Nurseries calculate liquid feed for containers.
Turf care
Turf managers scale foliar feeds to sprayer tanks.
Injector stock tanks
Growers mix concentrate for 1:100 or 1:200 injectors.
Home gardens
Gardeners dose watering cans per label.