Water-Soluble Fertilizer Calculator

Your details

Pick a common formula or choose Custom to enter your own N-P2O5-K2O values.
The nutrient you want to hit a specific concentration for. The dose is calculated from this element; all other nutrient concentrations follow.
ppm means mg per litre (mg/L). mmol/L is the molar equivalent, used in scientific and hydroponic contexts.
The concentration of the chosen nutrient you want in the final solution.
ppm
Total volume of diluted solution you need to prepare.
L
Fertilizer to addStandard feeding (150-300 ppm N)
10

Dry fertilizer weight to dissolve in the stated volume to hit the target concentration.

Rate per unit volume1
N in solution200ppm
P in solution87.3ppm
K in solution166ppm
Ca in solution0ppm
Mg in solution0ppm
N (ppm)200
P (ppm)87.3
K (ppm)166
Ca (ppm)0
Mg (ppm)0

Dissolve 10.00 g into 10 L of water.

  • Dissolve 1.000 g of fertilizer per L to replicate this recipe for any batch size.
  • This solution contains 200.0 ppm N, 87.3 ppm P, and 166.0 ppm K.
  • The nitrogen level is in the standard vegetative/fruiting feeding range used by most greenhouse and hydroponic programs.
  • Always dissolve the fertilizer in a portion of the final water volume first, then top up, to avoid clumping and salt stratification.

Next stepMeasure electrical conductivity (EC) after mixing as a quick sanity check - a 200 ppm N solution with a 20-20-20 fertilizer typically reads around 1.2-1.5 mS/cm.

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