🌊 Pool Salt Calculator
Enter your pool volume, current salinity, and target level to estimate how much salt to add, in pounds, kilograms, and full 40-lb bags, rounded down so you top up rather than overshoot.
💧 Dial In Your Salinity
Before you add any chemical
- Read the whole product label before each use and follow it. The label, not this calculator, sets the dose and the strength (CDC).
- Never mix chlorine products with acid: CDC warns this could create toxic gases. Never mix different pool chemicals, including different types of chlorine, with each other or anything else (CDC).
- Calcium hypochlorite (cal-hypo) and trichlor can react violently, causing fire or explosion (US EPA). Never put one in a feeder, floater or bucket that held the other.
- If the label says to pre-dissolve, add the chemical to water, never water to the chemical: CDC warns a violent, potentially explosive reaction can occur.
- Store each chemical separately in its original labeled container, dry, out of direct sunlight and below 95°F (35°C), in a locked area children and animals cannot reach (CDC).
- CDC ranges: free chlorine at least 1 ppm in pools (at least 2 ppm with cyanuric acid stabilizer) and at least 3 ppm in hot tubs; pH 7.0 to 7.8. Test chlorine and pH before anyone swims.
- After raising chlorine, keep everyone out until a test shows the level the label allows (one EPA-registered liquid chlorine label says below 4.0 ppm).
What is a Pool Salt Calculator?
It works out how many pounds of salt a saltwater pool needs to reach the salinity its chlorine generator wants. Give it your volume, the current salinity from a test strip or the cell's display, and your target, and it calculates the salt required — then converts it into kilograms and 40-lb bags.
A salt chlorine generator turns dissolved salt into chlorine, so keeping salinity in the right band is what keeps the whole system sanitising. Add salt in stages, brush it in, run the pump, and re-test — these are estimates, and it's always safer to under-add and top up than to overshoot.
❓ Frequently Asked Questions
What salinity should a saltwater pool be?
Most salt chlorine generators run best around 3,000–3,500 ppm, with 3,200 ppm a common target — that's the default here. Too little salt and the cell can't produce chlorine; too much can trigger a fault or accelerate corrosion. Always check the ideal range printed on your specific generator.
What kind of salt do I add?
Use pool-grade sodium chloride — evaporated, granulated salt that's at least 99% pure with no anti-caking agents, iodine, or additives. Avoid rock salt and water-softener pellets, which dissolve slowly and can leave residue. It usually comes in 40-lb bags, which is why the calculator gives you a bag count.
How do I add the salt?
Turn on the pump, broadcast the salt slowly across the deep end (or the shallow end of an above-ground pool), and brush it around to help it dissolve rather than piling on the floor. Run the pump for 24 hours before testing again. Add salt in stages toward the target — you can always add more, but you can only lower salinity by draining and refilling.
Will rain or splash-out change my salinity?
Yes. Salt doesn't evaporate, so it stays put as water evaporates — but heavy rain, backwashing, splash-out, and refilling all dilute it. Re-test every few weeks and top up as needed. This calculator handles a current reading, so you only ever add the difference back up to target.