Chlorine Dosage Calculator
Enter your pool details to calculate the exact amount of chlorine needed to reach your target ppm.
Safety — Never Mix Chemicals
- Never mix chlorine products together — combining different chlorine types can cause fire or explosion.
- Always add chemicals to water, never water to chemicals.
- Add chlorine to the pool with the pump running, preferably in the evening to reduce UV degradation.
- Wait at least 4 hours (ideally overnight) after shocking before swimming.
- Wear gloves and eye protection when handling all pool chemicals.
Chlorine Dosage Formulas
The amount of chlorine needed depends on your pool's volume, the current free chlorine level, and the concentration of the product you're using.
Liquid Chlorine (10% sodium hypochlorite): 1 gallon raises 10,000 gallons by approximately 1 ppm. Formula: oz = (target − current) × gallons ÷ 10,000 × 128.
Granular Chlorine (65% calcium hypochlorite): 1 lb raises 10,000 gallons by approximately 7 ppm. Formula: lbs = (target − current) × gallons ÷ 10,000 ÷ 7.
Chlorine Tablets (90% trichlor): Best for maintenance, not fast correction. Each 3-inch tablet dissolves slowly and adds roughly 1–3 ppm per week depending on pool size. Use a floating dispenser or automatic feeder.
Always retest your water 4–8 hours after adding chlorine to confirm levels have reached your target.