Pool Salt Calculator
(How Much Salt to Add to a Saltwater Pool)
Enter your pool's size and its current and target salt levels to find how many pounds and bags of salt to add, or how much water to replace if the pool is too salty.
Pool shape
Add shallow and deep end depths and divide by two
Read from a salt test strip or digital tester. Use 0 for a new pool
Check your chlorine generator's manual. Many run near 3,000–3,400 ppm
Result
💡 Formula Guide
How Much Salt a Saltwater Pool Needs
A saltwater pool needs enough dissolved salt for its chlorine generator to work, and the amount to add depends on your pool's volume and how far the current salt level is from the target. The generator, also called a salt cell, passes the salty water over electrically charged plates to make chlorine. If the salt is too low the cell slows or shuts down and algae can take hold, and if it is too high it can cause corrosion and false readings. A pool salt calculator takes the guesswork out of the amount, so you avoid over-buying or overshooting.
The 8.34 is the weight of a US gallon of water in pounds, and the 1,000,000 comes from the definition of parts per million. A quick check: a 10,000-gallon pool from 0 to 3,200 ppm needs 10,000 × 8.34 × 3,200 ÷ 1,000,000 = 266.9 lb, which is about seven 40-pound bags. A 15,000-gallon pool needs about 400 lb, or ten bags.
Working Out Pool Volume
The largest source of error is the volume. Pool volume in gallons is the volume in cubic feet times 7.48. Use the average depth for a pool with a sloping floor by adding the shallow and deep end depths and dividing by two.
| Shape | Volume in gallons | Example |
|---|---|---|
| Rectangle | Length × Width × Avg Depth × 7.48 | 32 × 16 × 5 ft = 19,149 gal |
| Round | π × (Diameter ÷ 2)² × Depth × 7.48 | 24 ft across, 4 ft deep = 13,535 gal |
| Oval | Length × Width × Avg Depth × 5.9 | About 0.785 of the same rectangle |
| Known volume | Use the builder's or manufacturer's figure | Enter it directly in the calculator |
Full example. A 32 × 16 ft rectangular pool with a 5 ft average depth holds about 19,149 gallons. If a test shows 400 ppm and the target is 3,200 ppm, you need to raise the level by 2,800 ppm: 19,149 × 8.34 × 2,800 ÷ 1,000,000 = about 447 lb, or 12 bags of 40 lb once rounded up. A round pool 24 ft across and 4 ft deep holds about 13,535 gallons and needs roughly 361 lb (10 bags) to go from 0 to 3,200 ppm.
Choosing the Target Salt Level
Salt chlorine generators are designed around a working range, and most operate somewhere between roughly 2,700 and 3,400 ppm. Some manufacturers specify a slightly lower or higher target, for example around 3,000 ppm for one brand and 3,400 ppm for another, so the number in your manual beats any general figure. Set that value as the target in the calculator and the amount updates. If your manual lists a range, aim for the middle of it: this leaves room for small dilution from rain and top-ups without dropping below the cell's minimum.
💡 Tip: add about 80% of the calculated amount first, wait a day, then test and top up. Salt cannot be removed by any chemical, only diluted, so it is safer to approach the target from below.
Adding Salt and Fixing a High Reading
Turn the pump on so the water circulates, then pour or broadcast the salt around the pool, ideally in the shallow end or over several spots, and brush it so it dissolves. Leave the pump running for a day. Retest with a strip or meter before adding more, since undissolved salt on the bottom can give a low reading. Follow your generator's instructions on whether to switch the chlorinator off while salt dissolves.
If the level is above target, the calculator shows the share of water to replace: 1 − (target ÷ current). At 4,000 ppm with a 3,200 ppm target that is 20%. Drain that amount, refill with fresh water and retest. Because refilling also dilutes other chemicals, rebalance the water afterwards. Check with your local rules about where pool water can be discharged.
Practical Tips and Limits
- Buy pool-grade salt. Choose high-purity sodium chloride sold for pools, in bags of a known weight, so you can turn pounds into bags easily.
- Retest after rain or refills. Fresh water lowers the salt level, so recalculate the amount to bring it back to target.
- Use a second test. Compare the chlorinator's reading with a test strip or digital meter, since built-in displays can drift.
- This is an estimate. Pool dimensions are rarely perfect, and an uneven floor can throw off the volume. If in doubt, add less, test and top up.
Running a pool also has an electricity cost: try the Electricity Bill Calculator to estimate what the pump adds to your bill. For a related home project, see the Recessed Lighting Calculator.
Frequently Asked Questions About Pool Salt
How much salt do I need for a saltwater pool?
Salt (pounds) = pool gallons × 8.34 × (target ppm − current ppm) ÷ 1,000,000. For a 10,000-gallon pool starting at 0 ppm and aiming for 3,200 ppm, that is about 267 pounds, roughly seven 40-pound bags. The calculator does this for any volume and salt level.
What salt level should a saltwater pool have?
It depends on the chlorine generator. Most salt systems work in a range of roughly 2,700 to 3,400 ppm, with about 3,200 ppm often quoted as a typical target, but manufacturers differ, so use the value in your generator's manual and set it as the target above.
How do I work out my pool's volume in gallons?
For a rectangle, multiply length × width × average depth in feet, then multiply by 7.48 gallons per cubic foot. For a round pool use π × (diameter ÷ 2)² × depth × 7.48. For an oval, multiply length × width × depth by about 5.9. If you use average depth you can handle a sloping floor: add the shallow and deep end depths and divide by two.
Where does the 8.34 in the formula come from?
A US gallon of water weighs about 8.34 pounds. Multiplying gallons by 8.34 gives the pounds of water, and one part per million of salt in that water means one pound of salt for every million pounds of water, hence the division by 1,000,000.
What if my pool has too much salt?
Salt does not evaporate or filter out, so the only fix is dilution: drain part of the pool and refill with fresh water. The fraction to replace is 1 − (target ÷ current). At 4,000 ppm with a 3,200 ppm target, replace about 20% of the water.
Can I use table salt?
Use salt sold for pools, usually labelled as sodium chloride at high purity with no additives. Table salt and some water-softener products can contain iodine, anti-caking agents or other additives that are not meant for pool water, so check the bag and your equipment manual.
How long after adding salt should I retest?
Run the pump and let the water circulate for about a day so the salt dissolves and mixes evenly, then test again before adding more. Testing straight away often shows a misleading reading because the salt has not spread through the pool.
Why does my chlorinator show a different salt level than my test?
Built-in readouts can drift, especially as the cell ages or gets scaled. Confirm with a separate test strip or digital meter and follow the generator maker's guidance if the two disagree.
Last Updated: September 2026 | The salt formula is standard water chemistry (8.34 lb per gallon). Target salt levels vary by chlorine generator, so follow your equipment manual.