Pool Chlorine Calculator

Enter the pool volume in gallons, the current and target free chlorine in ppm and the product you use to see how much to add.

Amount to add30.7 fl oz
In gallons0.24 gal
In milliliters908 mL

Don't know the volume? Use the pool volume calculator. Safety: never mix chlorine products with each other or with acid, add chemicals to the water (not water to chemicals), keep swimmers out until levels are back in range and follow the product label. Bleach strength drops with age, so the actual rise may be lower.

How the dose is calculated

1 ppm is 1 mg per liter. The chlorine needed is the ppm increase × the pool volume in liters. That amount is divided by the product strength: 12.5% liquid chlorine contains about 12.5 g of available chlorine per 100 mL, and 65% cal-hypo contains 65 g per 100 g.

Typical free chlorine levels

Many pool guides recommend 1–3 ppm of free chlorine for residential pools, higher when using cyanuric acid (stabilizer). Shocking raises it much higher temporarily. Test the water before and after adding chemicals.

Frequently asked questions

How much liquid chlorine to raise 1 ppm in 10,000 gallons?

About 10.2 fl oz of 12.5% liquid chlorine or 12.8 fl oz of 10% liquid chlorine.

How much cal-hypo to raise chlorine 1 ppm?

About 2 oz of 65% cal-hypo per 10,000 gallons.

Can I use household bleach?

Yes, if it is plain unscented bleach. It is weaker (about 6%), so you need roughly twice as much as 12.5% liquid chlorine.

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