Potassium PPM Calculator
Potassium is the quality nutrient — fruit size, flavor, and disease resistance all ride on it. Fruiting crops want 200–300 PPM. This gives you the grams.
Calculator
Potassium PPM Calculator
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Potassium is the quality nutrient — fruit size, flavor, and disease resistance all ride on it. Fruiting crops want 200–300 PPM. This gives you the grams.
How to use this calculator
- Enter volume.
- Enter target K PPM.
- Enter fertilizer K%.
- Get grams.
The formula
Labels show K₂O — elemental K = K₂O × 0.83.
What the inputs mean
The target is the concentration you want, in PPM. The volume is how much liquid you are treating. The potassium content, elemental k (%) corrects for product strength, because most products are not 100% active ingredient. The result tells you exactly how much potassium fertilizer to add.
Worked example
100 L, 250 PPM K, potassium sulfate at 50% K₂O (≈41.5% K): 250 × 100 ÷ 1,000 ÷ 0.415 ≈ 60 g.
Quick reference
| Stage | Typical K PPM |
|---|---|
| Vegetative | 150–200 |
| Fruiting | 200–300 |
Elemental K.
Where you will actually use this
K demand spikes during fruiting; guessing leaves quality on the table.
- Fruiting crops
- Turf stress tolerance
- Greenhouse production
Mistakes that give wrong answers
- Reading K₂O as elemental K
- K excess blocking magnesium uptake
Key takeaways
- Formula: K fertilizer (g) = Target K PPM × Volume (L) ÷ 1,000 ÷ K fraction
- Remember: Elemental K.
- Watch out for: Reading K₂O as elemental K
- Next step: run your own numbers in the calculator above, then verify with a measurement — calculated values are only as good as the inputs.
Frequently asked questions
What potassium PPM for fruiting?
200–300 PPM typically.