Pool Salt Calculator
Find out exactly how much salt your saltwater pool needs. Most salt chlorine generators work best at 3,200 ppm (acceptable range 2,700–3,400 ppm — always check your cell's manual).
How the math works
One gallon of water weighs 8.34 pounds, so:
- Salt (lbs) = (Target ppm − Current ppm) × Gallons × 8.34 ÷ 1,000,000
- 40-lb bags = lbs ÷ 40 (most pool salt is sold in 40-lb bags)
Example: a 12,000-gallon pool going from 0 to 3,200 ppm needs 3,200 × 12,000 × 8.34 ÷ 1,000,000 ≈ 320 lbs of salt — about 8 bags.
Tips before you add salt
- Use pool-grade salt (99%+ pure sodium chloride) — avoid rock salt or water-softener salt with additives.
- Pour salt around the perimeter with the pump running, then brush to help it dissolve.
- Re-test 24 hours after adding. Salt reads low while still dissolving.
- If your level is already above ~4,000 ppm, don't add salt — partially drain and refill to lower it.
Frequently asked questions
How much salt does a 10,000 gallon pool need?
From 0 ppm to 3,200 ppm: about 267 lbs, or roughly 6–7 forty-pound bags. If your pool already has some salt in it, use the calculator above with your current reading.
What if my salt level is too high?
Salt doesn't evaporate. The only way to lower it is to drain part of the pool and refill with fresh water. Use the calculator to see how far over target you are before draining.
Do I need salt again after rain or backwashing?
Heavy rain can dilute salinity slightly, and every backwash removes salted water. Re-test after big events — top-ups are usually small (20–60 lbs).