Build a fertilizer recipe
Choose three main ingredients for the exact solver. Add an optional fixed additive, then let the calculator solve masses, filler space, and cost.
Example data table
This sample shows a 100 kg, 10-10-10 blend using Urea, MAP, MOP, and limestone filler.
| Component | Analysis | Mass (kg) | N Contribution (kg) | P2O5 Contribution (kg) | K2O Contribution (kg) |
|---|---|---|---|---|---|
| Urea | 46-0-0 | 17.140 | 7.884 | 0.000 | 0.000 |
| MAP | 11-52-0 | 19.231 | 2.115 | 10.000 | 0.000 |
| MOP | 0-0-60 | 16.667 | 0.000 | 0.000 | 10.000 |
| Limestone Filler | 0-0-0 | 46.962 | 0.000 | 0.000 | 0.000 |
Formula used
1. Target nutrient mass = batch size × target percentage ÷ 100.
2. Additive nutrient mass = additive mass × additive analysis ÷ 100.
3. The solver then finds the three core ingredient masses from this matrix equation:
[n1 n2 n3] [x1] [required N after additive] [p1 p2 p3] × [x2] = [required P2O5 after additive] [k1 k2 k3] [x3] [required K2O after additive]
4. Filler mass = total batch − additive mass − x1 − x2 − x3.
5. Total cost = sum of each component mass × unit cost.
How to use this calculator
- Enter the total batch size you want to prepare.
- Type the target N, P2O5, and K2O percentages for the finished fertilizer.
- Select three core ingredients. Use presets or switch any slot to custom.
- Add a fixed additive only when you already know that exact mass belongs in the blend.
- Set a filler name and filler cost so the remaining batch space is priced correctly.
- Submit the form. Review solved masses, nutrient contributions, cost, chart, and downloads.
FAQs
1) What does the target analysis mean?
It is the final fertilizer grade of the whole batch. A 10-10-10 target means the finished mix contains 10% nitrogen, 10% P2O5, and 10% K2O by weight.
2) Why can a recipe become impossible?
Some ingredient sets cannot span all three nutrients, or they solve to negative masses. Very high targets can also exceed the batch before filler is added, which makes the blend infeasible.
3) Why does filler appear in the output?
Filler occupies any unused batch mass after nutrients are met. It helps dilute concentrated ingredients so the finished mix still matches the requested total weight and analysis.
4) Can I use organic ingredients?
Yes. Pick custom ingredients and enter their guaranteed analyses. The math works the same, but organic nutrient release in soil may differ from the label, so field performance can lag behind the formula.
5) Are phosphorus and potassium entered as elemental forms?
No. This calculator uses fertilizer-label convention: phosphorus as P2O5 and potassium as K2O. Enter the same basis shown on your ingredient bags or product sheets.
6) What is the optional fixed additive for?
Use it for micronutrient blends, conditioners, or any ingredient whose mass is already decided. The calculator subtracts its nutrient contribution first, then solves the remaining NPK requirement.
7) Should the three target percentages add up to 100?
No. Most fertilizer grades total far less than 100 because carriers, fillers, moisture, and other materials occupy the remaining mass. The solver automatically calculates that leftover space as filler.
8) How can I reduce blend cost?
Try cheaper nutrient sources, lower expensive additive amounts, or adjust the target grade to a less concentrated formula. Comparing cost per kilogram helps you spot blends that are mathematically valid but financially inefficient.