Pool Chlorine Dose and Cost Calculator

Reviewed for 2026, updated September 8, 2026.

Estimates how much liquid chlorine, cal-hypo or dichlor to add to raise free chlorine to a target level, what that dose costs and what it adds up to over a month of visits.

Your numbers

Pool volumegallonsFor a rectangle: length x width x average depth in feet x 7.5. Use the number from your service log if you already have it.Current free chlorineppmThe free chlorine reading from your test kit at the start of the visit.Target free chlorineppmThe level you want to leave the pool at; higher targets are common for hot weather or high stabilizer.Chlorine productPick the product on your truck. The percentage is the available chlorine printed on the label.Product price$ per gal or lbEnter your price per gallon for liquid chlorine, or per pound for granular products.Doses per monthdosesHow many times a month you add this dose to this pool; weekly service is about 4. Results update as you type.

Your estimate

Free chlorine increase needed...

Amount to add...

Cost of this dose...

Chlorine cost per month for this pool...

Estimates only. Assumptions are listed below, and you can change every input.

Every pool stop starts with a free chlorine reading and a decision: how much to add. Guess low and the pool is green by the next visit; guess high and you burn product and money on every account. This calculator gives you the dose for a specific pool volume and a specific rise in free chlorine, in the units you actually measure with, and puts a dollar figure on it so you can see what chlorine really costs per pool.

The estimate is straight chemistry. Raising one part per million of free chlorine in a pool means adding one pound of available chlorine for every million pounds of water, and water weighs about 8.34 pounds per gallon. The tool converts that requirement into fluid ounces of liquid chlorine or ounces by weight of granular product based on the strength you select, then multiplies by your price to get the cost of the dose and the monthly total for the number of doses you enter. Real pools have chlorine demand from sun, swimmers and debris, so the reading at the next visit will always be lower than the number you dosed to.

How to use this tool

Enter the pool volume in gallons, then the free chlorine reading you just took and the level you want to reach.
Select the chlorine product on your truck and enter what you pay per gallon of liquid or per pound of granular.
Read the dose in fluid ounces or ounces by weight, add it, and use the monthly cost to check whether that account is priced to cover its chemicals.

What the math assumes

Pool water is assumed to weigh 8.34 pounds per gallon, so one ppm of free chlorine in one million pounds of water equals one pound of available chlorine.
Liquid chlorine strength is treated as trade percent, meaning grams of available chlorine per 100 milliliters, which is how 10% and 12.5% sodium hypochlorite are commonly labeled.
Granular products are dosed by the available chlorine percentage you select (73%, 65% or 56%) with full dissolution and no product wasted.
The dose assumes ideal mixing and no chlorine demand from sunlight, swimmers, algae or debris; the actual reading at the next visit will be lower than the target.
Cost is your entered price multiplied by the product used; taxes, delivery and the price difference between a full jug and a partial jug are not included.

Frequently asked questions

How much 12.5% liquid chlorine raises free chlorine by 1 ppm in 10,000 gallons?

Using 8.34 pounds per gallon of water and 12.5% trade strength, the tool gives about 10.2 fluid ounces. Most field rules of thumb land between 10 and 11 ounces, so if your habit is different by a little, that is normal rounding.

Why is the reading lower than my target at the next visit?

Sunlight, bather load and organic debris consume chlorine every day, and the calculator does not model that demand. Many techs dose above their minimum so the pool still has free chlorine at the end of the week; stabilizer level and shade change how fast it drops.

Can I use this to clear a green pool?

You can use it to calculate a large rise in ppm, but a green pool consumes chlorine as fast as you add it, so plan on testing and dosing several times rather than relying on a single calculated dose.

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