Calculator
Use the mode selector to match your input type.
Formula used
- ppm (P) is calculated as mg of elemental P ÷ liters, which equals mg/L.
- Label phosphate conversion uses molar mass ratios: P = P2O5 × 0.4364 and P2O5 = P × 2.291.
- For fertilizer labels: mg P2O5 = mg fertilizer × (%P2O5 ÷ 100), then convert to elemental P.
- Target mode reverses the steps to estimate fertilizer needed for a chosen ppm.
Note: Soil test “ppm” and solution “ppm” are not identical measurements; this tool focuses on mg/L mixing math.
How to use this calculator
- Select a mode that matches your known values.
- Enter total solution volume, then fill the visible inputs.
- Choose rounding and enable steps if you want transparency.
- Press Calculate to view results above the form.
- Use CSV or PDF export for logs, records, or sharing.
Example data table
| Scenario | Inputs | Output (approx.) |
|---|---|---|
| Fertilizer label mixing | 10 g fertilizer, 10% P2O5, 10 L | P ≈ 43.64 ppm; P2O5 ≈ 100.00 ppm |
| P2O5 mass known | 5 g P2O5 in 20 L | P ≈ 109.10 ppm; P2O5 ≈ 250.00 ppm |
| Target dose planning | Target 30 ppm P, 10 L, 10% P2O5 | Fertilizer needed ≈ 6.87 g |
Use “Load example inputs” to prefill a common fertilizer scenario.