How Much Salt for Saltwater Pool
Opening your pool this spring or topping up after heavy rain? Use this free pool salt calculator to find out exactly how much salt for a saltwater pool you need. Enter your pool volume (or dimensions), your current salt reading, and your target ppm to get the pounds of salt plus how many 40-lb bags to buy.
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How to use this calculator
Start with your pool volume. If you know your gallons from your pool paperwork or installer, enter it directly. Otherwise switch to "Dimensions," pick your pool shape, and measure length, width, and average depth in feet โ for sloped floors, measure the shallow and deep ends and average them.
Next, enter your current salt level from a salt test strip or digital salt meter reading in ppm (parts per million). A fresh fill on city water usually reads close to 0 ppm. Set your target next: most salt-chlorine generators want 2,700โ3,400 ppm, and 3,200 ppm is the standard default โ but check your chlorinator manual, since some brands differ.
The calculator instantly shows how many pounds of pool salt to add and how many 40-lb bags to buy. If your current reading is already at or above your target, you'll see zero โ add nothing, because salt can only be lowered by draining water.
How it works
The math is simple concentration dosing. Water weighs about 8.34 lb per gallon, and ppm means "pounds of salt per million pounds of water." To raise your pool by a given number of ppm, you need:
Salt (lb) = pool gallons ร 8.34 ร (target ppm โ current ppm) รท 1,000,000
For example, a 15,000-gallon pool going from 0 to 3,200 ppm needs 15,000 ร 8.34 ร 3,200 รท 1,000,000 = 400.32 lb, which rounds to 400 lb โ ten 40-lb bags. The bag count is rounded up from the rounded pounds, so you always buy enough.
Pool volume from dimensions is length ร width ร average depth in cubic feet, converted at 7.5 gallons per cubic foot (we round 7.48052 slightly for simplicity; the difference is negligible for salt dosing). Oval pools use length ร width ร 0.785 ร depth, and round pools use ฯ ร (diameter รท 2)ยฒ ร depth. These are estimates based on perfect shapes โ real pools with stairs, benches, and sun shelves hold a little less, so treat the result as an estimate and retest after adding salt.
Frequently asked questions
How much salt does a saltwater pool need?
Most salt-chlorine generators call for 2,700โ3,400 ppm, and 3,200 ppm is the common default. For a typical 15,000-gallon pool starting with no salt, that works out to about 400 lb of pool salt (ten 40-lb bags). Enter your own pool volume and test-strip reading above for an exact number.
How do I figure out my pool's gallons from its dimensions?
Measure length, width, and average depth in feet. Rectangle: length ร width ร average depth ร 7.5. Oval: (length ร width ร 0.785) ร average depth ร 7.5. Round: 3.14 ร (diameter รท 2)ยฒ ร average depth ร 7.5. We use 7.5 gallons per cubic foot (the exact figure is 7.48052), which is close enough for salt dosing.
Can you put too much salt in a saltwater pool?
Yes โ over-salting can corrode metal parts, ladders, and stone coping, and it can shorten your salt cell's life. If your test shows you are already at or above your target ppm, add no salt. To lower salt, the only reliable fix is draining some water and refilling with fresh water.
Should I add all the salt at once?
No. Add it in thirds: spread a third of the salt around the deep end with the pump running, wait 24 hours, then retest before adding more. Never pour salt through the skimmer โ it can damage the salt cell and clog equipment. Brush any piles sitting on the floor until they dissolve.
How often should I test the salt level?
Test monthly with salt test strips or a digital salt meter, and any time you top off the pool, backwash heavily, or get heavy rain โ all of these dilute salt. Salt does not evaporate with the water, so you usually only add salt once per season plus small corrections.