Calculator
Formula used
This calculator treats free chlorine in ppm as mg/L:
- Δppm = max(0, target − current)
- Total chlorine (mg) = Δppm × volume(L)
- Total chlorine (g as Cl₂) = (Δppm × volume(L)) / 1000
- Product mass (g) = (Cl₂ g ÷ (available%/100)) × lossFactor
- Tablets needed = product mass (g) ÷ tablet weight (g)
Loss factor helps match real-world conditions like sunlight and organic load.
How to use this calculator
- Measure your tank or pond volume in liters or gallons.
- Test current free chlorine, or set it to 0.
- Pick a target ppm suitable for your situation.
- Choose a tablet preset or enter custom tablet details.
- Set a loss factor (start with 1.10 if unsure).
- Calculate, then add in portions and retest later.
Example data table
| Scenario | Volume | Current (ppm) | Target (ppm) | Tablet preset | Loss factor | Approx tablets |
|---|---|---|---|---|---|---|
| Garden tank refresh | 5,000 L | 0.5 | 2.0 | Trichlor ~200 g | 1.10 | ~0.10 |
| Small pond cleanup | 2,000 L | 0.0 | 1.5 | Dichlor ~20 g | 1.20 | ~0.32 |
| Tools sanitizing batch | 50 L | 0.0 | 10.0 | Cal-hypo ~300 g | 1.05 | ~0.003 |
Examples are illustrative. Always follow label directions and local guidance.