How It Works
This calculator works in 4 steps.
Enter the stock strength
Type the × value of the concentrated stocks.
Enter the reservoir volume
Type liters or gallons of water in the reservoir.
Enter the target strength
Type 1× or a fraction such as 0.5× for seedlings, as the feed plan specifies.
Read the stock volumes
The calculator returns volume of A and B, mL per liter, and expected EC.
The Formula
The formula multiplies reservoir volume by the target strength and divides by the stock strength.
V_stock = V_res × X_target / X_stockmL/L = 1,000 × X_target / X_stockEC ≈ EC_water + EC_1× × X_target- V_res:
- Reservoir volume
- X_stock / X_target:
- Stock and target strength
- EC_1×:
- EC contribution of 1× nutrients
A 50 L reservoir at 1× from 100× stocks needs 500 mL of A and 500 mL of B, added one at a time with mixing between.
Conversion Table
The conversion table gives A and B volumes for 6 reservoir sizes at 1× strength.
| Stock strength | Reservoir | Stock A | Stock B | Dose per liter (each) |
|---|---|---|---|---|
| 100× | 10 L (2.642 gal) | 100 mL | 100 mL | 10 mL/L |
| 100× | 50 L (13.21 gal) | 500 mL | 500 mL | 10 mL/L |
| 200× | 100 L (26.42 gal) | 500 mL | 500 mL | 5 mL/L |
| 250× | 20 L (5.283 gal) | 80 mL | 80 mL | 4 mL/L |
| 100× | 378.5 L (99.99 gal) | 3,785 mL | 3,785 mL | 10 mL/L |
| 50× | 5 L (1.321 gal) | 100 mL | 100 mL | 20 mL/L |
What Is the Hydroponic Stock Dilution Calculator?
The Hydroponic Stock Dilution Calculator is a tool that scales concentrated nutrient stock solutions, such as 100× A and B stocks, to the reservoir volume and returns the volume of each stock to add. Each stock is added separately to water, never mixed concentrate to concentrate.
Two-part nutrient systems keep calcium (stock A) apart from sulfates and phosphates (stock B), since the concentrates would form insoluble precipitates if combined. The calculator uses the stock strength from the formulation, such as 100× or 200×, and reports the expected electrical conductivity (EC) when the user enters the EC of 1× solution.
Common Uses
There are 5 main uses of this calculator.
Reservoir mixing
Growers prepare full-strength nutrient solution.
Injector setup
Greenhouses set dosing injectors for 100× stocks.
Seedling feeding
Growers prepare 0.25× to 0.5× solutions.
Research systems
Plant scientists prepare Hoagland-type solutions from stocks.
Reservoir top-ups
Growers dose stocks for added water volume.