Salt Calculator
Enter your pool volume and current and target salt readings to estimate how many pounds of pool salt to add for your salt-water chlorinator.
Salt to add
Buy 4 bags and do not pour the whole last one: add 5.1 lb from it. Add salt in stages, circulate, and re-test before adding more.
How the dose is calculated
A part-per-million reading is a concentration by weight, and a US gallon of water weighs about 8.34 pounds. So the pounds of salt needed to raise the level by a given ppm is: (target ppm − current ppm) × pool gallons × 8.34, divided by one million. For example, raising a 10,000-gallon pool by 100 ppm takes about 8.3 lb of salt — a figure that matches the standard rule of thumb published across salt-system dosing charts.
Add salt gradually around the perimeter of the pool with the pump running, and let it fully dissolve and circulate (often several hours) before re-testing, since a fresh reading taken too soon can under-report the true level.
Frequently Asked Questions
What salt level does my salt-water pool need?
It depends on your specific chlorinator model — most residential units are designed to run somewhere between about 2,700 and 3,400 ppm, with many defaulting to a target around 3,200 ppm. Check your chlorinator's manual or the label on the control unit for its exact recommended range before dosing.
How do I find my pool's current salt level?
Most salt-cell control panels display a live salt reading. You can cross-check it with a dedicated salt test strip or a drop-based salt test kit, since cell sensors can drift out of calibration over time.
What kind of salt should I use?
Use salt sold specifically for pool chlorinators — a high-purity (typically 99%+) sodium chloride, non-iodized, without anti-caking additives that can cloud the water or interfere with the cell. Avoid table salt, rock salt, or water-softener salt, which often carry additives not meant for a pool system.
Does salt ever need to be removed instead of added?
Not by chemical means — there's no practical additive that lowers salt. If your reading is above the chlorinator's maximum, the only way down is diluting with fresh water (partially draining and refilling), which also happens naturally over time through backwashing, splash-out, and rain overflow.
Dosing guidance only, not a substitute for your chlorinator's manual or a professional water test. Always confirm the recommended salt range for your specific system before dosing, and re-test after the salt has fully dissolved and circulated.
Before you add any chemical
- CDC: "Read 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; this could create toxic gases." Never mix different pool chemicals, including different types of chlorine, with each other or with anything else.
- Add the chemical to water, never water to the chemical. CDC: "NEVER add water to the pool chemical because a violent (potentially explosive) reaction can occur."
- Store each chemical separately, closed in its original labeled container, below 95°F (35°C). CDC: "Separate incompatible chemicals (for example, acid and chlorine)." and "Keep chemicals secure and away from children and pets."
- CDC ranges: "The typical range is 1-4 ppm for chlorine" and pH 7.0 to 7.8. Test chlorine and pH before anyone swims, and at least twice a day while the pool is in use (CDC).
- Doses here round DOWN and assume US gallons (a UK gallon is 1.2 US gallons). Add part, circulate, re-test, and keep everyone out of the water until the test reads inside the range.
Pool safety comes first
- Pool Safely (CPSC): "A fence of at least four feet in height should surround the pool or spa on all sides and should not be climbable for children." Fence all four sides, separating the pool from the house, with self-closing, self-latching gates (CDC).
- Pool Safely: "Always watch children when they’re in or near water, and never leave them unattended." Name one adult as the Water Watcher.
- Drain covers: Pool Safely says "never enter a pool or spa that has a loose, broken or missing drain cover." Powerful drain suction "can even trap an adult". Public pools and spas must meet the Virginia Graeme Baker Pool & Spa Safety Act.
- Pumps, heaters and other pool equipment need GFCI protection, and CPSC says to "Have an electrician who is qualified in pool and spa repairs inspect and upgrade your pool, spa or hot tub".
- CDC: hot tub "Water temperature should not be higher than 104°F (40°C)."