Water Soluble Fertilizer Calculator

Water Soluble Fertilizer Calculator

Instructions: The water soluble fertilizer calculator (also a fertilizer ppm calculator or a hydroponic nutrient formula calculator) generates a recipe for a water-soluble fertilizer solution.

Water Soluble Fertilizer Calculator is useful to generate the complete recipe for a water-soluble fertilizer. To obtain quick results, you need to enter details in the input fields like fertilizer presents, fertilizer labels, and other requirements.

Fertilizer presets
Fertilizer Label
Label Type
Your requirements
Desired element
Mass Concentration
Molar Concentration in
Nutrient solution recipe
Fertilizer rate in
Volume of diluted solution
Fertilizer weight in

Water Soluble Fertilizer (Fertilizer PPM) Calculator: This handy hydroponic nutrient formula calculator provides the recipe for a water-soluble fertilizer. Here you can learn the ways & tips to mix fertilizer solutions in one of the essential fertilizer calculations. This online water-soluble fertilizer calculator saves your time, money and growing plants.

What are Water Soluble Fertilizers?

Water-soluble fertilizers are fertilizers that are 100% soluble in water. These are applied through foliar spray and fertigation methods in which nutrients are readily absorbed and used in the plant system without wastage through evaporation, leaching and runoff.

There are two important components of the water-soluble fertilizer's label N-P-K numbers and "guaranteed analysis".

The N-P-K numbers are 3 large numbers you will see on the package, as of 20-8-20. These numbers (nitrogen, phosphorus, and potassium) are the primary nutrients and per cent of the fertilizer's weight. The nutrients available are nitrogen (N), potash (K₂O), and phosphate (P₂O5). The percentage is 20% of the bag's weight is composed of nitrogen, 8% is phosphate, and 20% is potash.

How to use Water Soluble Fertilizer Calculator?

Making hydroponic nutrients is easy with the water-soluble fertilizer calculator. You need to follow the below-listed instructions.

  • Give the N-P-K numbers or the elemental percentage numbers in the Fertilizers Label section.
  • Select the element for which you have a target concentration in mind.
  • Enter the concentration values as weight concentration or molar concentration.
  • Make the volume of the diluted solution to your mixing container size.
  • Record how much dry fertilizer is needed to achieve your concentration.
  • Check the output to know how much of every element will make your recipe.

Steps to Find Nutrient Solution Recipe to make 200 ppm Nitrogen

Question: If you have a 100 L water tank, calculate how much fertilizer to add to achieve 200 ppm nitrogen?


For this question, we will use a soluble fertilizer with 20-8-20 label.

Rewrite ppm as mg/L

Nitrogen concentration (mg/L) = 200 ppm = 200 mg/L nitrogen

Find the final fertilizer concentration

Fertilizer concentration (mg/L) = nitrogen concentration (mg/L)/percent weight

= 200 mg/L N/0.2

= 1000 mg/L = 1 g/L

Find the fertilizer weight to be added

Fertilizer = Fertilizer concentration * water volume

= 1 g/L of fertilizer * 100 L

= 100 g

So, we should add 100 g fertilizer to 100 L of water to achieve 200 ppm N.

Calculate other elements' concentrations

P2O5 concentration = fertilizer concentration * percent weight of P2O5

K2O concentration = fertilizer concentration * per cent weight of K2O

The atomic weight of phosphorus = weight of P2O5/2.29133

The atomic weight of Potassium = weight of K2)/1.204

Finally, the atomic weight of N is 14.007, P is 30.9, K is 39.09 and K is 15.9.

How to Mix Water Soluble Fertilizer?

The simple and five useful tips to mix water-soluble fertilizer are along the lines:

  1. Take a sterile stirring stick of inert material and clean tank.
  2. Dissolve the fertilizer in a container before adding it to your tank for easier mixing.
  3. If you are mixing more than one fertilizer, careful about the precipitate compounds in heavy concentrations.
  4. Measure and manage pH value after adding fertilizer into the tank.
  5. Use an opaque container and store the solution in a dark place.

FAQs on Water Soluble Fertilizer Calculator

1. How to mix water-soluble fertilizer with water?

When mixing water-soluble fertilizer with water, add less than 1/2 of the total volume required into the container, then add the fertilizer. Mix and add water to increase the total stock volume to the required level.

2. Is water-soluble fertilizer the same as liquid fertilizer?

Both water-soluble fertilizers and liquid fertilizers are available in the form of crystals. Potassium nitrate is an example of water-soluble fertilizer. Fish emulsion and compost tea are examples of liquid fertilizers.

3. What are the steps to convert concentrations from mmol to ppm?

The formula to convert concentrations from mml to ppm is ppm (mg/L) = molar concentration (mmol/L) * molar mass (g/mol).

4. What are different water sources you can use in water-soluble fertilizers?

The different water sources are rainwater, tap water, groundwater, and deionized water. If you are growing setup recirculates water irrigation, you must aware of the salt levels of your water sources.