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CalcChef

Pool Chlorine Dose Calculator

How much chlorine to add to a pool: grams = ppm rise × litres ÷ 1,000, shown as 12% liquid chlorine, 6% bleach, trichlor, dichlor or cal-hypo. How it works

Use the Pool Chlorine Dose Calculator

Chlorine product

Volume unit

Range: 100 to 500,000 gal

Set from the product; use the figure on your container, it falls as liquid chlorine ages. Bleach labelled 6% by weight is about 6.2% trade strength (g per 100 mL); the default 6 gives a slightly larger dose than 6.2 would.

Range: 0 to 30 ppm

Range: above 0 to 30 ppm

Stabilizer level from your test. Any CYA, or a product that contains it, raises the CDC minimum free chlorine.

Liquid chlorine 12% to add
32 fl oz
Equals 946 mL

Never mix different pool chemicals with each other or with any other substance, and never mix chlorine products with acid (it can create toxic gases). Only pre-dissolve a chemical when the label says to, and then add the chemical to water; never add water to a pool chemical. Read and follow the product label, and wear goggles and gloves. (CDC, Use Pool Chemicals Safely.)

Raises free chlorine by 2 ppm in 15,000 gal (56,781 L): 113.6 g of available chlorine.

Minimum free chlorine for this pool: 2 ppm. CDC: at least 2 ppm free chlorine in pools that use cyanuric acid (CYA) or a product that contains it; at least 3 ppm in hot tubs. pH 7.0 to 7.8.

Method: 1 ppm is 1 mg of chlorine per litre, so grams of available chlorine = ppm × litres ÷ 1000 (1 ppm in 10,000 US gallons is 37.85 g, or 1.335 oz, of 100% available chlorine). A dry product is that weight divided by its available-chlorine fraction; a liquid is divided by its strength (trade % × 10 g/L).

Typical strengths are the tool's assumption (labels: trichlor about 90%, dichlor 56%, cal-hypo 65% minimum available chlorine). Chlorine demand, sunlight and water chemistry are not modelled: retest after the product has circulated.

About the Pool Chlorine Dose Calculator

Raising free chlorine by 2 ppm in a 15,000 gallon pool takes 32 fl oz (946 mL) of 12% liquid chlorine, or 64 fl oz of 6% bleach. The pool chlorine calculator works from 1 ppm = 1 mg per litre: grams of available chlorine = ppm rise × litres ÷ 1,000, divided by the strength of the product you choose.

Product to raise free chlorine by 1 ppm, by pool size

Product5,000 gal10,000 gal15,000 gal20,000 gal30,000 gal
Liquid chlorine 12%5.3 fl oz (158 mL)10.7 fl oz (315 mL)16 fl oz (473 mL)21.3 fl oz (631 mL)32 fl oz (946 mL)
Household bleach 6%10.7 fl oz (315 mL)21.3 fl oz (631 mL)32 fl oz (946 mL)42.7 fl oz (1,262 mL)64 fl oz (1,893 mL)
Trichlor 90%0.74 oz (21 g)1.48 oz (42 g)2.23 oz (63 g)2.97 oz (84 g)4.45 oz (126 g)
Dichlor 56%1.19 oz (34 g)2.38 oz (68 g)3.58 oz (101 g)4.77 oz (135 g)7.15 oz (203 g)
Cal-hypo 65%1.03 oz (29 g)2.05 oz (58 g)3.08 oz (87 g)4.11 oz (116 g)6.16 oz (175 g)

Liquids by volume; trichlor, dichlor and cal-hypo by weight, with the available chlorine percent on their labels. Multiply by the ppm rise you need. The strengths are typical values: enter the one on your container.

Frequently asked questions

How much liquid chlorine raises a pool by 1 ppm?
In 10,000 gallons, 10.7 fl oz (315 mL) of 12% liquid chlorine, or 21.3 fl oz (631 mL) of 6% bleach. Both carry 37.9 g of available chlorine, which is 1 mg per litre in 37,854 litres of water.
How much bleach do I add to my pool?
Twice the volume of 12% liquid chlorine: 64 fl oz (1,893 mL) of 6% bleach raises 15,000 gallons by 2 ppm. Bleach labelled 6% by weight is about 6.2% trade strength (grams per 100 mL); entering 6.2 gives 61.9 fl oz.
How much trichlor, dichlor or cal-hypo do I need?
For +2 ppm in 15,000 gallons: 4.45 oz of trichlor (90% available chlorine), 7.15 oz of dichlor (56%) or 6.16 oz of cal-hypo (65%), all by weight. Trichlor and dichlor contain cyanuric acid, so each dose also raises the CYA of the water.
What chlorine level should a pool have?
The CDC says at least 1 ppm free chlorine in pools, at least 2 ppm when cyanuric acid (stabilizer) or a product that contains it is used, and at least 3 ppm in hot tubs, with pH 7.0 to 7.8. The calculator shows the minimum that applies and flags a target below it: 2 ppm with the default CYA of 30 ppm, 1 ppm with no CYA and no stabilized product.
Why is the chlorine still low after I add the dose?
The dose covers only the ppm rise you entered. Chlorine demand, sunlight and the rest of the water chemistry are not modelled, and liquid chlorine loses strength as it ages, so retest after the product has circulated and enter the strength printed on your container.
Can I mix pool chemicals before adding them?
No. The CDC pool chemical poster says never to mix pool chemicals with each other or with anything else, and never to mix chlorine products with acid. Pre-dissolve only when the label says to, and then add the chemical to water, never water to the chemical.

Turning a chlorine test into an amount to add

Enter the free chlorine reading from your test kit as the current ppm and the level you want as the target. The dose depends on the ppm rise, the pool volume and the product strength, nothing else. The cyanuric acid (CYA) reading does not change the amount: it picks the CDC minimum shown beside the result, 2 ppm when CYA is above 0 or the product is trichlor or dichlor, 1 ppm otherwise, and a target below it is flagged. Add the dose with the pump running and test again once it has circulated.

How the dose is calculated

available chlorine (g) = ppm rise × litres ÷ 1,000

liquid (mL) = grams ÷ (trade % × 10) × 1,000

dry product (g) = grams ÷ (available chlorine % ÷ 100)

1 ppm is 1 mg per litre. Trade percent is grams of available chlorine per 100 mL, so 12% liquid chlorine holds 120 g per litre.

Example: 15,000 gal is 56,781 L. Raising it from 1 to 3 ppm takes 2 × 56,781 ÷ 1,000 = 113.6 g of available chlorine, and 113.6 ÷ 120 g per litre is 946 mL, 32 fl oz of 12% liquid chlorine.

The CDC minimums shown with the result: 1 ppm free chlorine in pools, 2 ppm with cyanuric acid, 3 ppm in hot tubs, pH 7.0 to 7.8.

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