How the pool chlorine calculator works
Raising free chlorine by 1 ppm takes about 1.33 ounces (38 grams) of chlorine for every 10,000 gallons of water.
Products aren't pure chlorine, so that amount is divided by the strength on the label. Liquid chlorine is usually 10% to 12.5%, cal-hypo 65% to 73%, and dichlor about 56%.
Liquid chlorine strength is labeled by volume, so it is measured in fluid ounces: 12.8 fl oz of 10% liquid raises 10,000 gallons by 1 ppm. Granular products are measured by weight.
The cost uses your price per gallon of liquid, or per pound of granular.
Tips from the trade
- Liquid chlorine loses strength in heat and sunlight. A jug that sat in a hot truck all week may be well under its label strength, so store it cool and shaded.
- Cal-hypo adds calcium and dichlor adds stabilizer (CYA) every time you use them. Watch those readings if you rely on them every week.
- Know your gallons. A 10% mistake in pool size is a 10% mistake in every dose.
When you need more than a free pool chlorine calculator
This calculator answers one quick question. Running a business means doing it on every job, with your own rates saved and a quote you can send.
Pool chlorine calculator questions
How much liquid chlorine do I add to raise free chlorine 1 ppm?
About 10 fl oz of 12.5% liquid chlorine per 10,000 gallons, or about 13 fl oz of 10%. This calculator works it out for your pool size and target.
What free chlorine level should a pool have?
It depends on your stabilizer (CYA) level. Higher stabilizer needs a higher free chlorine level to work well. Follow your local health code and the guidance for your sanitizer.
Is this a substitute for reading the label?
No. Use it to estimate the dose, then follow the product label and retest after the water has circulated.