Enter your water details to calculate a dose.
The result will appear here after you press Calculate.
Calculator
Example data table
These examples assume 1.0 ppm chlorine to remove, 100% purity, and 10% safety margin. Actual values vary by water chemistry and testing.
| Water volume | Chlorine removed | Neutralizer | Recommended dose | Notes |
|---|---|---|---|---|
| 20 L | 1.0 ppm | Sodium thiosulfate | ~49 mg | Good for watering cans. |
| 100 L | 1.0 ppm | Sodium thiosulfate | ~245 mg | Typical barrel batch. |
| 200 L | 1.0 ppm | Ascorbic acid | ~550 mg | May lower pH slightly. |
| 1,000 L | 1.0 ppm | Sodium thiosulfate | ~2.45 g | Small tote or tank. |
| 3,785 L (1,000 US gal) | 0.5 ppm | Ascorbic acid | ~5.20 g | Large garden storage. |
Note: Example math uses the same formula described below and the default neutralizer ratios.
Formula used
1) Chlorine mass to remove
Because ppm ≈ mg/L, total chlorine mass is:
chlorine_mg = (initial_ppm − target_ppm) × liters
This yields milligrams of chlorine to neutralize.
2) Neutralizer dose
Apply a mass ratio and adjust for product purity and safety:
neutralizer_mg = chlorine_mg × ratio
product_mg = neutralizer_mg ÷ purity × (1 + safety%)
Default ratios: sodium thiosulfate uses a practical mass ratio (~2.23:1), while ascorbic acid uses ~2.5:1 by mass.
Use Custom ratio if your product label specifies different dosing.
How to use this calculator
- Measure your container or tank volume and select the correct unit.
- Test your water for free chlorine, or use your supplier’s reported value.
- Set the target chlorine, usually 0 ppm for sensitive plants or compost tea.
- Choose a neutralizer and enter purity from the label, if applicable.
- If using a liquid solution, enter its strength to estimate milliliters.
- Press Calculate, then download CSV/PDF for recordkeeping.