Pool Chlorine Calculator
Enter your free chlorine (FC) test result and where you want it. Pick the product you have and the strength on its label.
Quick answer: To raise free chlorine by 1 ppm in a 10,000-gallon pool, add about 12.8 fl oz of 10% liquid chlorine, or about 2.1 oz of 65% cal-hypo.
Checked against 6 published sources (see them). Updated October 2026.
- Raises free chlorine by
- 2.0 ppm
- For
- 15,000 gallons
Liquid chlorine to raise free chlorine by 1 ppm
Using 10% liquid chlorine.
| Pool size | Amount |
|---|---|
| 5,000 gal | 6.4 fl oz |
| 10,000 gal | 12.8 fl oz |
| 15,000 gal | 19 fl oz (2.4 cups) |
| 20,000 gal | 26 fl oz (3.2 cups) |
| 25,000 gal | 1 qt |
| 30,000 gal | 1 qt 6 fl oz |
How it works
Raising chlorine by 1 ppm (part per million) in 10,000 gallons takes about 0.083 lb of pure chlorine. The calculator divides that by your product's strength, so weaker products need more.
Liquid chlorine is measured by volume. The % on the jug is grams of chlorine per liter, divided by 10. For example, 12% liquid chlorine takes about 10.7 fl oz per ppm per 10,000 gallons.
Dry products are measured by weight, using the available chlorine % printed on the label. Dichlor and trichlor also add stabilizer (cyanuric acid, CYA): about 0.9 ppm and 0.6 ppm of CYA for every 1 ppm of chlorine.
Tips
- Liquid chlorine loses strength as it sits, faster in heat. An old jug may need more. Retest after the pump has run for an hour.
- Pour liquid chlorine slowly into the water near a return jet with the pump running.
- Never mix chlorine products together or with acid, even in a bucket.
Sources
We checked the math on this page against:
- Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool
- Lucas County (Ohio) Health Department: Pool Chemistry Adjustments
- Pool & Hot Tub Alliance fact sheet: Sodium Hypochlorite
- Wojtowicz, "Swimming Pool and Spa Water Chemical Adjustments," Journal of the Swimming Pool and Spa Industry (2004)
- AQUA Magazine: Dichlor, the sanitizing stalwart
- ICC Building Safety Journal: Trichlor, the dependable pool performer
Frequently asked questions
How much liquid chlorine do I add to a 10,000-gallon pool?
About 10.7 fl oz of 12% liquid chlorine raises free chlorine by 1 ppm in 10,000 gallons. To go from 1 to 3 ppm, that's about 21 fl oz.
Can I use household bleach?
Yes, if it's plain unscented bleach with no additives. It's weaker than pool chlorine, so enter the strength from the label and the calculator adjusts.
What should free chlorine be?
The CDC says at least 1 ppm in pools, and at least 2 ppm if you use stabilizer (CYA). Many owners aim for 2–4 ppm. Hot tubs need at least 3 ppm.