NPK fertilizer calculator online
Enter your crop and water volume - the app calculates how many milliliters of each fertilizer to measure out. Precise doses without formulas or notebook tables.
with seeding rates
in diagnostics
in one app
to use
What is NPK and why count doses?
NPK - the three key "vitamins" for a plant: N - nitrogen (for green leaves), P - phosphorus (for roots) and K - potassium (for fruit and flavor).
Adding fertilizers by eye - the plant either starves or gets burned. The calculator takes a tested recipe and adjusts it to your water volume. All you need to do is measure the right amount with a measuring cup or syringe.
"By eye"
- Yellow or scorched leaves
- Wasted fertilizer and money
- No idea what went wrong
With calculator
- Exact milliliters for your volume
- Healthy plants and a good harvest
- Step-by-step instructions
Four tools in one app
Everything you need for plant nutrition - from calculating doses to finding out why leaves are turning yellow.
Dose calculator
Choose a crop, stage and volume - get milliliters of each fertilizer. The heart of the app.
Seeding rates
70 cropsHow much seed to sow per tray or bed - no overcrowding and no empty spots.
Diagnostics
25+ issuesLeaves yellowing or curling? Identifies the likely cause and what to adjust in the solution.
Concentrate recipe
Make a stock solution in advance - then simply dilute it with water as needed.
Live calculation example
Choose a crop, growth stage and solution volume - watch the doses update in real time. This is exactly how the app works, just simplified here.
Three simple steps to a ready solution
No formulas needed. All you need is a measuring cup and clean water.
Choose crop and stage
For example "Lettuce → Growth" or "Tomato → Fruiting". Each stage has its own nutrition recipe.
Enter the water volume
How many liters of solution you are preparing - 5, 20 or 100. The calculator recalculates doses for that exact amount.
Measure A → B → C
Add fertilizers one by one, stirring ~30 seconds between each. Check EC and pH at the end.
Ready-made nutrition recipes for every plant
All profiles are open right away: no sign-up, no login.
All crops
What the nutrition is made of
The app works with proven mineral fertilizers. Each one has its own "role" in nutrition. The numbers under the name are NPK: nitrogen · phosphorus · potassium.
Mixing order matters
Fertilizers are added one at a time and fully dissolved. Mixing "concentrates" directly causes them to precipitate and become useless.
Pour clean water
Room temperature, the full volume. Settled or filtered water is best.
Add group A and stir
Wait until fully dissolved.~30 sec
Then group B
Potassium and magnesium. Stir again until clear.~30 sec
Group C goes last
Calcium and iron are added at the very end, once everything else is dissolved.
Never mix directly
Calcinit (calcium) and Potanit (potassium) cannot be combined in concentrated form - they form an insoluble precipitate. Add them to water separately, at different steps.
Profile 1 - greens and microgreens
A simple three-step order. Suits lettuce, basil and culinary herbs.
Profile 2 - fruit, berries, flowers
Group D (phosphorus) is added for tomato, cucumber, pepper and strawberry in the fruiting stage.
Exact numbers for those who love detail
How much of each element should be in the solution (mg per liter) at different stages. The greens profile is fully open - the rest is in the app.
🥬 Profile 1 - Greens (lettuce, basil, herbs)
Values in mg/L. EC - target solution strength, mS/cm.
| Stage | N | P | K | Ca | Mg | Fe | EC |
|---|---|---|---|---|---|---|---|
| Seedling | 110 | 45 | 150 | 120 | 40 | 2.0 | 1.4 |
| Active growth | 150 | 50 | 200 | 150 | 48 | 2.5 | 1.8 |
| Before harvest | 120 | 45 | 180 | 130 | 45 | 2.2 | 1.6 |
🍅 Profile 2 - Fruit, berries and flowers
Tomato, cucumber, pepper, eggplant, strawberry, flowers.
Full tables by stage are in the calculator.
Open calculatorThe app on your phone - no App Store
The NPK calculator opens from the browser and adds to the home screen like a regular app. No store, no updates, no storage taken up.
iPhone · iPad
Safari browser- Open the site in Safari and tap the Share ⬆ button at the bottom of the screen.
- Scroll the menu and choose "Add to Home Screen".
- Tap "Add" - the icon will appear among your apps.
Android
Chrome browser- Open the site in Chrome. A banner "Add app" may appear at the bottom - tap it.
- Or open the ⋮ menu in the top right corner.
- Choose "Add to Home screen" and confirm.
Works without internet. After the first launch all recipes are stored on the phone - calculate doses right in the greenhouse or in the field, with no signal.
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The essentials, in short
Is it really free?
Yes, the calculator is free: no payments, no subscriptions, no sign-up.
Do I need internet to calculate?
No. After the first launch the app works offline - in a greenhouse, a basement, or anywhere without a connection. Internet is only needed for the first launch and updates.
I'm a beginner and afraid to mess something up. Is it complicated?
Not at all. You pick a crop and water volume, and the app shows ready milliliters and the order of steps. All the equipment you need is a measuring cup or syringe. An EC and pH meter are nice to have, but you can start without them.
Will it work for regular pots, not just hydroponics?
Yes. The solution suits watering seedlings, microgreens and potted plants. The recipes are universal - only the watering frequency changes.
Precise fertilizer doses - in a couple of taps
Open the calculator in the browser or install it on your phone. Free, in liters or gallons, no registration to get started.