Calculator
Pick a mode, enter values, then calculate. Use the export buttons after results appear.
All calculations are approximate.
Example data table
These rows show typical use cases. Use them to sanity-check your inputs.
| Mode | Input | Assumptions | Key outputs |
|---|---|---|---|
| Convert | 2 mg/L as NH3 | Per liter basis | ≈ 2.12 mg/L as NH4+, ≈ 1.64 mg/L as N |
| Speciation | TAN 1.5 mg/L as N | pH 8.2, 25°C | NH3 fraction rises; NH3 is a smaller share at lower pH |
| Solution | 10% NH3, 250 mL | Density 0.96 g/mL | ≈ 24 g NH3, ≈ 19.7 g N |
| Convert | 5 g as N | Mass basis | ≈ 6.08 g NH3, ≈ 6.44 g NH4+ |
Example numbers are rounded and may differ slightly from your results.
Formula used
This calculator uses molecular-weight relationships and an ammonia speciation approximation.
Molecular weights
Used for mass-based conversions.
- NH3 ≈ 17.0305 g/mol
- NH4+ ≈ 18.0385 g/mol
- N ≈ 14.0067 g/mol
Core conversions
Examples (mass or mg/L basis).
- N = NH3 × (14.0067 / 17.0305)
- NH4+ = NH3 × (18.0385 / 17.0305)
- NH3 = N × (17.0305 / 14.0067)
Speciation (NH3 fraction)
Approximation using pH and temperature.
- pKa = 0.09018 + 2729.92 / T(K)
- f(NH3) = 1 / (1 + 10^(pKa − pH))
- NH3-N = TAN-N × f(NH3)
Notes: ppm is treated as mg/L for dilute water solutions. Fertilizer equivalents use typical label nitrogen percentages (21% and 46%).
How to use this calculator
- Select a mode that matches your measurement source.
- Enter values and pick the correct basis and units.
- Optional: add volume to convert concentration into total mass.
- Click Calculate to view results above the form.
- Use CSV or PDF buttons to save a record.
Practical gardening reminder
Nitrogen affects growth strongly. Start small, monitor plant response, and avoid applying strong ammonia solutions directly to roots or foliage.