Pool Salt Calculator

Type your pool volume, the salt level you read now and the level you want. Get the pounds of salt and the bags to add.

How to calculate how much salt to add to a pool

Salt is measured in parts per million, or ppm. Your test gives the level you have now, and the manual of your salt chlorinator gives the level it needs. The difference between the two, the pool volume in gallons and one constant give the pounds to add.

Step	Formula
1. Salt to add (ppm)	target ppm − current ppm
2. Pounds of salt	gallons × ppm to add ÷ 120,000
3. Bags	pounds ÷ pounds per bag, rounded up

The 120,000 is the number of gallons of water that weigh about one million pounds, so one ppm in that much water is one pound of salt. The Indiana health department uses the same constant for chlorine, in its guide to adjusting pool chemicals. We checked the formula against the salt chart of Hayward, a maker of salt chlorinators. The printed version of that chart in Hayward’s Salt Facts sheet (hosted by a pool retailer) has 272 figures, from 8,000 to 40,000 gallons and from 0 to 3,000 ppm. The formula matches every one of them after rounding to whole pounds. We checked both in October 2026.

Example: a 15,000 gallon pool at 1,200 ppm

A pool holds 15,000 gallons and the test reads 1,200 ppm. The chlorinator is a Hayward unit, so the target is 3,200 ppm. Salt comes in 40 lb bags.

Step	Operation	Result
Salt to add	3,200 − 1,200	2,000 ppm
Pounds	15,000 × 2,000 ÷ 120,000	250 lb
Bags of 40 lb	250 ÷ 40 = 6.25, rounded up	7 bags
One bag raises the level	40 × 120,000 ÷ 15,000	320 ppm

Seven bags is 280 pounds, a little more than the 250 needed. Pouring all seven would bring the pool to 1,200 + 280 × 120,000 ÷ 15,000 = 3,440 ppm, above the 3,400 ppm top of Hayward’s range. Hayward’s sheet says to hold one or two bags in reserve, pour in the rest, and test again after the water has circulated. Its sheet says the salt display can take up to 24 hours of circulation to settle.

What salt level does a salt chlorinator need?

It depends on the maker, so check the manual of your unit. The two makers we read in October 2026 give different numbers.

Maker	Ideal	Range listed
Hayward	3,200 ppm	2,700 to 3,400 ppm
Pentair IntelliChlor (IC15 guide)	3,400 ppm	3,000 to 4,500 ppm

The Hayward figures come from its page How much salt do you add. The Pentair figures come from the IntelliChlor IC15 installation and user’s guide, and we did not read the manuals of other Pentair models. Other brands have their own numbers. If yours is not listed, choose “Custom target” in the calculator and type it. Hayward adds that a low level reduces the efficiency of the chlorinator, and that a high level can make it shut down.

Pounds of salt for common pool sizes

These figures are for a pool with no salt in the water, so they are the largest amount you would add. They use the formula on this page. For 8,000, 10,000, 20,000 and 30,000 gallons at 3,200 ppm they match Hayward’s chart after rounding.

Pool size	To 3,200 ppm	Bags of 40 lb	To 3,400 ppm	Bags of 40 lb
8,000 gal	213 lb	6	227 lb	6
10,000 gal	267 lb	7	283 lb	8
15,000 gal	400 lb	10	425 lb	11
20,000 gal	533 lb	14	567 lb	15
30,000 gal	800 lb	20	850 lb	22

Tips for adding salt

Test the water before you add anything. Hayward points out that the chlorine you add to a pool turns back into salt, so a pool that has been chlorinated before may already hold some.
Use the volume of your pool, not a guess. If you are unsure, work it out with the pool volume calculator.
Add the salt in two steps. Pour most of it, let it circulate, test, and add the rest only if the reading is still low.
Choose salt that is at least 99% sodium chloride. Hayward says salt is sold in bags of 40 to 80 pounds.
For a new plaster pool, Hayward’s sheet says to ask the applicator for the cure time before adding salt.
For chlorine itself, see the pool chlorine calculator.

Hayward quotes the package of Morton Pool Salt, which says a 40 pound bag is worth 480 ppm in a 10,000 gallon pool. That matches the formula, since 40 × 120,000 ÷ 10,000 = 480. The result box shows the ppm that one bag of your size raises in your pool, so you can compare it with the label.

Frequently asked questions

How do you calculate how much salt a pool needs?

Subtract your current salt level from the target, both in ppm. Multiply the result by the pool volume in gallons and divide by 120,000. That gives pounds of salt. A 15,000 gallon pool at 1,200 ppm that needs to reach 3,200 ppm takes 15,000 × 2,000 ÷ 120,000 = 250 pounds.

How much salt should a 10,000 gallon pool have?

For a Hayward chlorinator the ideal level is 3,200 ppm inside a range of 2,700 to 3,400 ppm. A 10,000 gallon pool that has no salt needs 267 pounds to reach 3,200 ppm. Pentair lists 3,400 ppm as ideal for its IntelliChlor unit, which takes 283 pounds in the same pool. Check the manual of your own chlorinator for its range.

How many 40 lb bags of salt do I need for my pool?

Divide the pounds from the result by 40 and round up. A 10,000 gallon pool going from 0 to 3,200 ppm needs 266.7 pounds, which is 6.67 bags, so 7 bags. The result box does this for any bag size you type.

How many bags of salt do I need for a 30,000 gallon pool?

From 0 to 3,200 ppm a 30,000 gallon pool takes 800 pounds, which is 20 bags of 40 pounds. If the pool already has some salt, enter the current ppm and the amount drops. Each 200 ppm already in the water saves 50 pounds in a 30,000 gallon pool.

What kind of salt should I use in a saltwater pool?

Hayward asks for salt that is at least 99% pure sodium chloride. Its sheet says to avoid rock salt sold as ice melt and any salt with more than 1% anti-caking agents such as yellow prussiate of soda or sodium ferrocyanide, because they can stain the pool. It names food grade salt, solar salt and water softener salt as the usual types.

Why do other pool salt calculators give a different number?

Two things change the result. The target differs, since Hayward uses 3,200 ppm and Pentair uses 3,400 ppm. The conversion factor also differs slightly. Pentair’s chart gives 284 pounds for a 10,000 gallon pool going from 0 to 3,400 ppm, while the formula on this page gives 283.3. The gap is about 0.2%, under one pound in a 10,000 gallon pool.

What if my salt level is already too high?

Adding salt will not help, and nothing you add can lower it. Hayward says the only way to lower the salt level is to dilute it, which means draining part of the pool and refilling with fresh water, because salt does not wear out, break down or evaporate. Test again after refilling.