Saltwater Pool Calculator
Saltwater pools use a chlorine generator that converts pool-grade sodium chloride into chlorine — so instead of adding liquid chlorine, you add salt. Enter your pool volume and current salt reading to find out exactly how many pounds and bags to add to reach your target salinity.
Your salt dosage will appear here
Enter your pool volume and salt level, then click calculate.
Dosage reference: salt needed by pool size
| Pool size | 0 → 3,200 ppm | 40 lb bags | 3,000 → 3,200 ppm (top-up) | 40 lb bags |
|---|---|---|---|---|
| 10,000 gal | 267.2 lbs | 7 | 16.7 lbs | 1 |
| 15,000 gal | 400.8 lbs | 11 | 25.1 lbs | 1 |
| 20,000 gal | 534.4 lbs | 14 | 33.4 lbs | 1 |
| 25,000 gal | 668.0 lbs | 17 | 41.8 lbs | 2 |
| 30,000 gal | 801.6 lbs | 21 | 50.1 lbs | 2 |
Quick Answer
Enter your pool volume, current salt reading (if known), and target ppm — the calculator gives you the exact pounds of pool salt to add, plus how many 40 lb or 50 lb bags to buy.
How It Works: Formula & Variables
lbs of salt = (Target ppm − Current ppm) × Gallons × 0.00000835
If you don't know your current salt level, the calculator assumes 0 ppm (fresh water).
Worked Examples
Example: New saltwater pool
A 20,000-gallon pool starting at 0 ppm targets 3,200 ppm. lbs = 3,200 × 20,000 × 0.00000835 ≈ 534 lbs, or about 14 bags of 40 lb pool salt.
Key Concepts
Salt doesn't evaporate: Levels only drop from splash-out, backwashing, and rain overflow — not from the salt cell generating chlorine.
Generator-specific targets: Always check your salt cell's manual — operating below the minimum range can damage the cell or stop chlorine production.
Common Mistakes
Using the wrong salt: Iodized table salt and rock salt contain additives that can clog the salt cell — use pool-grade NaCl only.
Adding it all at once without brushing: Undissolved salt can settle and stain the pool floor — brush periodically while it dissolves.
Frequently Asked Questions
Most salt chlorine generators operate best at 3,000–3,500 ppm. The exact target depends on your generator brand — Hayward recommends 3,200 ppm, Pentair 3,200–3,400 ppm, and Jandy 3,000–3,500 ppm. Check your manual for the precise figure.
Salt does not evaporate — you only lose it through splash-out, backwashing, and rainwater overflow. Top up at the start of each season and after heavy rain causes overflow. Test salt levels monthly.
Use pool-grade sodium chloride (NaCl), at least 99.8% pure. Do not use rock salt, iodised table salt, or solar salt with additives — impurities can clog the salt cell and cloud the water.
With the pump running, granular pool salt fully dissolves in 24–48 hours. Brush undissolved salt off the bottom if it sits for more than a few hours to avoid staining.
Yes. Drain and refill to dilute any cyanuric acid buildup, install a salt chlorine generator, then add salt to reach your target ppm. The water does not need to be changed entirely unless chemistry is badly off.
There is no chemical that removes salt. The only way to reduce salinity is to partially drain the pool and refill with fresh water, then retest and recalculate.