Pool Salt Calculator
Calculate how much salt to add to your saltwater pool. Enter gallons, current and target ppm, and get the pounds, kilograms and bags of salt needed.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Pool Salt Calculator Works
This calculator tells you how much salt to add to a saltwater pool to reach the salinity your chlorine generator needs. Enter your pool volume in gallons, your current salt level (from a test strip or digital reading), your target ppm, and the bag size you buy. It returns the salt needed in pounds and kilograms, plus the number of bags to purchase.
If your current level already meets or exceeds the target, the tool reports that no salt is needed, because salt can only be removed by draining and refilling.
The Formula
Salt to add (lbs) = (target ppm − current ppm) × gallons × 8.34 ÷ 1,000,000
Here 8.34 is the weight of one US gallon of water in pounds, and ppm (parts per million) is the same as milligrams of salt per liter by weight. Multiplying the total water weight by the ppm gap and dividing by one million converts that fraction into pounds of salt. To convert to kilograms, multiply pounds by 0.4536.
Worked Example
A 15,000-gallon pool currently at 1,000 ppm, with a target of 3,200 ppm, using 40-lb bags:
- ppm to raise = 3,200 − 1,000 = 2,200 ppm
- Salt = (2,200 × 15,000 × 8.34) ÷ 1,000,000 = ≈ 275 lbs
- Kilograms = 275 × 0.4536 = ≈ 125 kg
- Bags = ceil(275 ÷ 40) = 7 bags
Recommended Salt Levels
Most salt chlorine generators target a band around 3,200 ppm. Always defer to your unit’s manual, but these ranges are typical:
| Salinity (ppm) | Status |
|---|---|
| Below 2,700 | Too low — generator output drops |
| 2,700 – 3,400 | Ideal operating range |
| 3,200 | Common default target |
| Above 4,500 | Too high — risk of alarms and corrosion |
Add salt with the pump running, broadcasting it across the deep end so it dissolves evenly, and wait 24 hours before retesting. Add in stages rather than all at once: it is far easier to add more salt than to drain and refill a pool that overshot the target.
Frequently asked questions
How much salt do I add to my pool?+
Use salt to add (lbs) = (target ppm − current ppm) × gallons × 8.34 ÷ 1,000,000. For a 15,000-gallon pool going from 1,000 ppm to 3,200 ppm, that is (2,200 × 15,000 × 8.34) ÷ 1,000,000 ≈ 275 lbs, about seven 40-lb bags. Add salt gradually and retest.
What salt level should a saltwater pool be?+
Most salt chlorine generators run best at 3,000 to 3,500 ppm, with 3,200 ppm a common target. Always follow your specific generator's recommended range, since too little salt reduces chlorine output and too much can trigger a high-salt alarm or corrosion.
Why is the formula multiplied by 8.34?+
8.34 is the weight in pounds of one US gallon of water. Salinity in ppm means milligrams of salt per liter, which equals parts per million by weight, so multiplying the volume's weight by the ppm difference and dividing by one million gives the pounds of salt to add.
How many bags of salt do I need?+
Divide the pounds of salt required by your bag size and round up. Pool salt commonly comes in 40-lb bags, so 275 lbs needs ceil(275 ÷ 40) = 7 bags. This calculator does the rounding for you based on the bag size you enter.
What if my salt level is too high?+
You cannot remove salt with a chemical. The only way to lower salinity is to partially drain the pool and refill with fresh water, then retest. If your target is at or below the current level, this calculator shows that no salt should be added.