Pool Salt Calculator
Calculate exactly how much salt to add to your pool. Enter your pool volume, current salt level, and target ppm to get the precise weight and number of 40-lb or 50-lb bags needed.
Total water volume of your pool in gallons. Check your pool builder's paperwork or equipment manual. If unavailable, estimate using: length × width × average depth × 7.48 for a rectangular pool.
Your pool's current salt concentration in ppm. Test with a salt test strip, a digital salinity meter, or your salt chlorine generator's built-in display. If starting fresh with tap water, enter 0.
The salt level your chlorine generator requires. Most systems specify 2,700–3,400 ppm — check your equipment manual for the exact range. 3,200 ppm is the standard recommendation for most salt chlorine generators.
Salt to Add
Bag counts are rounded up to the nearest whole bag. Add salt with the pump running, pouring slowly around the perimeter. Allow 24 hours for full dissolution before retesting.
💡About this calculator▼
Salt water pools use a salt chlorine generator (SWG) to produce chlorine from dissolved salt. For the generator to work correctly, the salt level in your pool must stay within its specified operating range — typically 2,700–3,400 ppm for most systems, with 3,200 ppm as the common target.
This calculator tells you exactly how many pounds of pool salt to add to reach your target level, and converts that into 40-lb and 50-lb bag counts so you know exactly what to buy.
The calculator finds the salt deficit — the difference between your target and current salt level — then converts that into pounds using the weight of water (8.34 lbs per gallon). Bag counts are rounded up to the nearest whole bag.
Salt does not evaporate or break down. But it does get diluted over time: rain adds fresh water, backwashing removes pool water, and splashing carries water out. These events lower salt concentration gradually, which is why periodic retesting matters.
📐How it's calculated▼
Salt (lbs) = (Target ppm − Current ppm) × Pool Volume (gal) × 8.34 ÷ 1,000,000
8.34 lbs/gallon is the weight of water. Dividing by 1,000,000 converts the ppm mass ratio (parts per million by weight) into actual pounds of salt.
Bag counts are calculated by dividing total salt needed by bag size, then rounding up — you always need full bags, not fractions.
Reference rate:
• Per 10,000 gallons per 100 ppm increase: ~8.3 lbs of salt
📎Source: Standard pool chemistry: salt ppm calculation based on water density 8.34 lbs/gallon; salt chlorine generator operating ranges from Hayward, Pentair, and Jandy equipment manuals
🔍Finding your inputs▼
Pool Volume: Check your pool builder's paperwork or equipment manual. If unavailable, estimate using: length × width × average depth × 7.48 for a rectangular pool.
Current Salt Level: Test with a salt-specific test strip, a digital salinity meter, or your salt chlorine generator's built-in readout. Test strips for salt water pools measure in 200 ppm increments — for greater accuracy, use a digital meter or bring a water sample to a pool store. If you're filling a new pool or one that has never had salt added, enter 0.
Target Salt Level: Check your salt chlorine generator's owner manual for its required operating range. Most systems (Hayward, Pentair, Jandy) specify 2,700–3,400 ppm. Using a target outside that range will reduce chlorine output or trigger low-salt fault codes. 3,200 ppm is the standard midpoint recommendation when no specific target is given.
⚠️Special situations▼
Salt level is too high — need to dilute
Salt does not break down or get consumed by the chlorinator — the only way to lower salt concentration is dilution. Partially drain the pool (10–20% of volume is typical) and refill with fresh water. Retest after refilling and recalculating before adding any salt. Repeat if needed.
Salt reads low after heavy rain or refilling
Adding fresh water dilutes the salt concentration. After significant rain, auto-fill activity, or manually adding water to compensate for evaporation, retest your salt level and use this calculator to top it up. This is the most common reason pools need salt additions mid-season.
Generator showing a low salt error despite correct ppm reading
A low salt fault while the water tests in range usually means the generator's cell electrodes are scaled with calcium deposits, reducing conductivity. Clean the cell with a diluted muriatic acid solution (follow the manufacturer's cleaning procedure) and retest. If the fault persists after cleaning, the cell may be nearing the end of its lifespan.
Pool has algae or cloudy water
Do not add salt to a pool with active algae or severely imbalanced water. Shock the pool first, clear the algae, and get pH and alkalinity into range before adjusting salt. Adding salt to an unbalanced pool can make water chemistry harder to stabilize.
❓Common questions▼
What salt level should my pool be at?
Most salt chlorine generators operate best between 2,700 and 3,400 ppm. The specific target depends on your equipment — check your generator's manual for its recommended range. When in doubt, 3,200 ppm is a safe, widely-applicable target that works for most residential systems. Running below 2,500 ppm causes the generator to underperform or shut off; running above 4,000 ppm can accelerate corrosion on metal components.
What type of salt should I use?
Use pool-grade or water softener salt that is at least 99.8% pure sodium chloride (NaCl) with no additives. Avoid salt marketed as "yellow bag" (contains anti-caking agents that can cloud water) or iodized table salt. Granular salt dissolves faster than pellets — either works, but granular is easier to add. Do not use solar salt with impurities or rock salt, which can leave residue.
Does pool salt evaporate or need regular replacement?
Salt does not evaporate — water evaporates, but the salt stays behind. When you add fresh water to compensate for evaporation, you're actually diluting the salt concentration. Salt is lost from the pool through splash-out, backwashing the filter, and overflow during rain. Most pools need a partial salt top-up once or twice per season, not a full replacement.
Why does my salt chlorine generator show a low salt error when my salt is in range?
The most common cause is a scaled or dirty cell. Salt chlorine generators measure salt by electrical conductivity — calcium and mineral deposits on the electrodes interfere with that reading, causing false low-salt readings even when the water tests correctly. Clean the cell according to the manufacturer's procedure. If the error continues after cleaning, the cell may need replacement.
How long does it take for salt to dissolve after adding it?
Most pool-grade salt fully dissolves within 24 hours with the pump running. Granular salt dissolves faster than large pellets. After adding salt, run the pump continuously and brush any granules off the pool floor to speed dissolution. Do not retest with a test strip or meter until at least 24 hours have passed — readings taken while salt granules are still dissolving will be inaccurate and may lead to over-dosing.