Pool Chlorine Dosage Calculator
Enter your pool volume, the free chlorine rise you want and the strength of your chlorine product, and this calculator returns the exact dose in grams, ounces and pounds. It works for a routine top-up of a couple ppm or a heavy shock of ten ppm or more, and it adjusts automatically for cal-hypo, dichlor or any product once you type its available chlorine percent. Everything is computed from parts per million as milligrams per liter, so the number is grounded in the actual chemistry rather than a rough rule of thumb.
How to calculate a chlorine dose
- Type your pool water volume into the 'Pool volume (gallons)' field.
- Set the free chlorine rise you want in the 'Raise free chlorine (ppm)' field.
- Enter the product's available chlorine in the '(%)' field, or leave 65 for calcium hypochlorite.
- Read the large headline figure for the product mass in grams.
- Check the cards below for the same dose in ounces and pounds plus the pure chlorine content.
- Press 'Copy result' to grab a one-line summary for your log or shopping list.
Examples
Routine dose: 10,000 gallon pool, raise 2 ppm with cal-hypo
10,000 gallons, +2 ppm, 65% available chlorine
About 116.5 g of product (4.11 oz, 0.257 lb); pure chlorine 75.71 g
Shock: 20,000 gallon pool, raise 10 ppm with cal-hypo
20,000 gallons, +10 ppm, 65% available chlorine
About 1,164.7 g of product (41.09 oz, 2.568 lb); pure chlorine 757.08 g
Weaker product: 15,000 gallon pool, raise 3 ppm with dichlor
15,000 gallons, +3 ppm, 56% available chlorine
About 304.2 g of product (10.73 oz, 0.671 lb); pure chlorine 170.34 g
Frequently asked questions
How much chlorine raises free chlorine by 1 ppm?
One ppm is 1 milligram of chlorine per liter of water, so the pure chlorine needed equals your volume in liters divided by 1000. A 10,000 gallon pool holds about 37,854 liters, which works out to roughly 37.9 grams of pure chlorine for each 1 ppm rise.
What does the available chlorine percent field mean?
It is the fraction of a product that is active chlorine, which is why weaker products need more weight for the same result. Calcium hypochlorite is around 65 percent, dichlor around 56 percent and trichlor around 90 percent. The tool divides the pure chlorine figure by this fraction to get the actual product mass.
Does this work for liquid chlorine or bleach?
The calculator returns a mass, so it fits granular and powdered products best. Liquid chlorine and bleach are sold by concentration in percent by weight, not a dry mass, so you would need to convert the gram figure to a volume using the liquid's density and strength before pouring.
Can I use it to shock the pool?
Yes. Shocking is simply a larger ppm rise, often 10 ppm or a level several times your combined chloramine reading. Enter the higher target and the product mass scales in a straight line with it.
Why does it convert gallons to liters?
Parts per million in water is defined as milligrams per liter, so the arithmetic is cleanest in metric. The tool multiplies your gallons by 3.785412 to get liters, then works in milligrams and converts the final answer back to grams, ounces and pounds.
Does it account for chlorine that gets used up or burned off by sun?
No. It calculates the pure dose to reach a target on a fresh test, and it does not model demand from organics, sunlight or a low stabilizer level. Add your dose, run the pump, then retest and top up if the reading falls short.
What if I only know the pool size in liters or cubic meters?
The input is US gallons, so convert first. Divide liters by 3.785412, or multiply cubic meters by about 264.17, to get the gallons figure to enter.
Are there input limits or errors?
Volume, ppm rise and available chlorine must all be positive numbers, and available chlorine cannot exceed 100 percent. If a field is blank, zero or out of range the tool shows a short message instead of a dose.
Is my data private?
Yes. The calculation runs entirely in your browser with no account and no upload, so your pool details never leave your device.
Learn more
- Free chlorine, ppm and how pool dosing math works
Understand what a ppm of free chlorine really means, how product strength changes the dose, and how to reach a target level without guesswork.
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