Pool Salt Calculator
Work out how much salt to add to a salt water pool, in pounds and 40 lb bags. If the salt is already too high, it tells you how much water to drain and refill.
Not sure? Use the pool volume calculator.
Enter 0 for a new or fresh-filled pool
Check your salt cell’s manual
To raise salt from 2,700 to 3,200 ppm:
Pool salt to add
Pure sodium chloride, 99%+
63 lb
40 lb bags
Rounded up to whole bags
2
If the pool is more than about 500 ppm low, add half, let it circulate for 24 hours, retest, then add the rest.
Before you add: confirm the reading with a salt test strip or meter, not only the cell’s display. Pour salt around the shallow end with the pump running, brush it off the floor, and let it dissolve for 24 hours before trusting a new reading.
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How the pool salt formula works
Salt is measured in parts per million (ppm) by weight. A gallon of water weighs 8.34 lb, so the pounds of salt you need are:
lb of salt = ppm to add × gallons × 8.34 ÷ 1,000,000
For example, raising a 20,000 gallon pool from 2,700 to 3,200 ppm is 500 × 20,000 × 8.34 ÷ 1,000,000 = about 83 lb, or three 40 lb bags.
Pool salt chart
Pounds of salt to raise the level by the amount shown.
| Pool size | +500 ppm | +1,000 ppm | +3,200 ppm |
|---|---|---|---|
| 10,000 gal | 42 lb | 83 lb | 267 lb |
| 15,000 gal | 63 lb | 125 lb | 400 lb |
| 20,000 gal | 83 lb | 167 lb | 534 lb |
| 25,000 gal | 104 lb | 209 lb | 667 lb |
| 30,000 gal | 125 lb | 250 lb | 801 lb |
The +3,200 ppm column is the start-up dose for a pool filled with fresh water.
Tips from the route
- Test before you add. A scaled cell reads low and is the most common reason pools get over-salted.
- Use pool salt (sodium chloride, 99% or purer) without anti-caking agents or iodine.
- Salt only leaves with water: backwashing, splash-out, rain overflow and draining. A pool that keeps dropping salt fast is usually losing water, so check for a leak.
- Keep the rest of the water balanced too. Salt pools tend to drift high on pH, so keep an eye on the LSI to protect the cell and plaster.
Frequently Asked Questions
How much salt do I need for my pool?
Multiply the ppm you need to add by your gallons, then by 8.34, and divide by 1,000,000 to get pounds. A new 15,000 gallon pool filled to 3,200 ppm needs about 400 lb, which is ten 40 lb bags plus part of an eleventh. A pool that tests 2,700 ppm needs about 63 lb to reach 3,200 ppm.
What should the salt level be in a salt water pool?
Most residential salt chlorine generators are designed for roughly 3,000 to 3,500 ppm, and 3,200 ppm is a common target. Check the manual or the label on your cell, because the range differs between brands and models.
How many bags of salt for a 10,000 gallon pool?
Starting from fresh water, about 267 lb, or seven 40 lb bags, to reach 3,200 ppm. To raise an existing pool by 500 ppm, about 42 lb.
How do I lower the salt level in my pool?
Salt does not evaporate or get used up, so the only way to lower it is to drain part of the water and refill with fresh water. To go from 4,000 to 3,200 ppm, replace 20% of the water. Rain and splash-out lower it slowly over a season.
Why does my salt cell read differently from my test strip?
Cells estimate salt from conductivity and water temperature, and a scaled or ageing cell reads low. Confirm with a salt test strip or a calibrated meter before adding salt, so you do not overshoot because of a dirty cell.
How long after adding salt can I swim or test?
You can swim right away. Run the pump and brush undissolved salt off the floor. Wait about 24 hours for the salt to fully dissolve and mix before retesting or trusting the cell reading.