Pool Salt Calculator
Work out exactly how much salt your saltwater pool needs. Enter the pool volume, your current salt reading and the level your chlorinator wants, and get the pounds, kilograms and number of bags to add.
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Not sure? Use the pool volume calculator.
From a salt test strip, meter or your chlorinator display. Use 0 for fresh water.
Check your salt cell manual. Many cells ask for about 2,700-3,400 ppm.
How to use the Pool Salt Calculator
- Enter the pool volume in US gallons or liters.
- Test the salt level and enter the current reading in ppm (0 for a freshly filled pool).
- Enter the target from your salt cell manual, typically around 3,200 ppm.
- Pick your bag size and, if you like, the price per bag.
- Add the salt with the pump running, brush it in, and retest after 24 hours.
Pool salt formula
Salt level is measured in parts per million (ppm) by weight: 1 ppm is 1 mg of salt in each kilogram of water. Because a liter of water weighs about 1 kg and a US gallon weighs about 8.345 lb, the amount of salt is:
kg of salt = liters × (target ppm − current ppm) ÷ 1,000,000
lb of salt = US gallons × (target ppm − current ppm) × 8.345 ÷ 1,000,000
Example: a 15,000 gallon pool reads 1,200 ppm and the cell wants 3,200 ppm. Salt = 15,000 × 2,000 × 8.345 ÷ 1,000,000 = 250 lb, which is 6.3 bags of 40 lb, so buy 7 bags and hold back part of the last one.
Pool salt chart: pounds to reach 3,200 ppm
| Pool size | From 0 ppm | From 1,000 ppm | From 2,000 ppm | From 2,800 ppm |
|---|---|---|---|---|
| 5,000 gal | 134 lb | 92 lb | 50 lb | 17 lb |
| 10,000 gal | 267 lb | 184 lb | 100 lb | 33 lb |
| 15,000 gal | 401 lb | 275 lb | 150 lb | 50 lb |
| 20,000 gal | 534 lb | 367 lb | 200 lb | 67 lb |
| 25,000 gal | 668 lb | 459 lb | 250 lb | 83 lb |
| 30,000 gal | 801 lb | 551 lb | 300 lb | 100 lb |
A 40 lb bag adds about 4,790 ppm divided by the pool size in thousands of gallons: roughly 480 ppm in 10,000 gal, 320 ppm in 15,000 gal and 240 ppm in 20,000 gal.
Tips for adding salt
- Test first, then add in steps. Add about three quarters of the calculated amount, circulate for a day, retest and top up. Removing extra salt means draining water.
- Pour salt around the shallow end or along the perimeter with the pump running and brush it until dissolved. Do not dump it straight into the skimmer unless your equipment maker says that is fine.
- Turn the chlorine cell off while new salt dissolves if your manual recommends it, then switch it back on once readings are stable.
- Know why salt drops. Salt is not consumed by chlorination; it leaves through splash-out, backwashing, draining and rain overflow. A big drop with none of those may point to a leak or a faulty sensor.
- Know your volume. The biggest error in any salt dose is a wrong pool size, so measure the pool or use the pool volume calculator.
Frequently asked questions
How much salt do I need for a 10,000 gallon pool?
To raise fresh water (0 ppm) to 3,200 ppm in 10,000 US gallons you need about 267 lb of salt, which is 7 bags of 40 lb (6.7 bags exactly). Each 40 lb bag raises a 10,000 gallon pool by about 480 ppm.
What is the formula for pool salt?
Pounds of salt = gallons × ppm increase × 8.345 ÷ 1,000,000, because a US gallon of water weighs about 8.345 lb and ppm means parts per million by weight. In metric, kilograms of salt = liters × ppm increase ÷ 1,000,000.
What salt level should a saltwater pool have?
It depends on the chlorine generator. Many cells are designed for roughly 2,700 to 3,400 ppm with about 3,200 ppm as the ideal, but some systems run lower or higher. Always use the range printed in your cell's manual or on the control panel.
How do I lower the salt level in my pool?
Salt does not evaporate, so you have to replace some water with fresh water. The fraction to drain is 1 − target ÷ current. For example, going from 4,000 to 3,200 ppm means replacing 20% of the water.
What kind of salt should I use?
Use pool salt: sodium chloride that is at least 99% pure, with no iodine, anti-caking agents or yellow prussiate. Fine granulated salt dissolves fastest. Rock salt and table salt with additives can stain surfaces or harm the cell.
How long does it take for pool salt to dissolve?
Granulated pool salt usually dissolves within a few hours with the pump running and some brushing, but wait about 24 hours of circulation before trusting a new reading. Many manufacturers suggest turning the cell off while the salt mixes in.
Why does my salt reading differ between my test strip and my chlorinator?
Strips, digital meters and cell sensors each have their own accuracy, and cell readings drift with water temperature and scale on the cell plates. Use one reliable test method consistently and add salt in steps rather than all at once.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.