What Is the Pool Salt Calculator?
Saltwater pools use a salt chlorine generator that converts dissolved salt into chlorine. To work properly, the water typically needs a salt concentration around 2,700–3,400 ppm (check your generator's manual). This calculator tells you exactly how many pounds and kilograms of salt to add to move from your current level to your target level.
How to Use It
Enter your pool volume in gallons, your current salt reading in ppm (use a test strip or your generator's display, or 0 for a new fill), and your target ppm. The calculator returns the salt needed in pounds, kilograms, and the number of standard 40 lb bags.
The Formula Explained
The core equation is $$\text{salt (lbs)} = \text{volume} \times (\text{target} - \text{current}) \times 8.345 \times 10^{-6}$$ One gallon of water weighs about 8.345 pounds, so one ppm (one milligram per kilogram, or part per million by weight) of salt in a gallon equals \(8.345 \times 10^{-6}\) pounds. Multiplying by the volume and the ppm gap gives the total salt to add.
Worked Example
For a 15,000-gallon pool currently at 0 ppm aiming for 3,200 ppm: $$15{,}000 \times 3{,}200 \times 8.345 \times 10^{-6} = \textbf{400.56 lbs}$$ or about 181.7 kg — roughly ten 40 lb bags.
FAQ
What if my current level is already above the target? You don't need to add salt; the result is shown as 0. To lower salt you must dilute by partially draining and refilling.
How fast does salt dissolve? Run the pump for 24 hours with the generator off so the salt fully dissolves and circulates before testing again.
What salt should I use? Use pure, food-grade or pool-grade sodium chloride (NaCl) that is at least 99% pure and contains no anti-caking or iodine additives.
