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Saltwater Pool Calculator

How much salt for an above ground pool

With a fresh fill, round pools measuring 12 to 33 feet wide take anywhere from 2 to 18 bags, with each bag holding 40 lb of salt. That assumes 4 feet of water depth. Intex calls for 3,000 ppm (parts per million, the number a salt test shows), while Hayward's manual lists 3,200 ppm. Pour in your 40 lb bags and let the pump circulate 24 hours before testing.

Don't know the gallons? Measure the pool
Pool shape

The gallons above fill in as you measure.

Example For 7,600 gallons, from 0 to 3,200 ppm. Type yours to see your bags.

Buy 6 bags of

Add 203 lb in all: pour 5 bags now, then 3 lb from bag 6 after you retest.

7,600 galSalt in the water (ppm)target 3,200now 06 bags
  1. Pump on. Pour it around the deep end, not into the skimmer.
  2. Brush any salt off the floor until it's gone.
  3. Run the pump 24 hours and test. Add the rest only if the reading is still short.
How this is worked out

Gallons = A × B × average depth × 7.5 for a rectangle, 6.7 for an oval and 5.9 for a round pool (diameter × diameter), the factors in Hayward's manual; 7.0 for a kidney (length × average width), from Inyo's sizing guide. Pounds of salt = (target ppm − your ppm) × gallons × 8.34 ÷ 1,000,000. A gallon of water weighs 8.34 pounds. Bags round up. In liters: kilograms = ppm difference × liters ÷ 1,000,000.

Salt needed by pool size

Two things set the salt you'll use: the pool's width and its depth. Every figure here assumes a round pool holding 4 feet of water.

All counts are 40 lb bags going into a fresh fill at 0 ppm. To get past 2,700 ppm, a 12 foot pool takes 80 lb, meaning 2 bags. Plan on 3.5 to 4 bags when a 15 foot pool must reach 3,200 ppm. With a 27 foot pool, you'll use 10 to 12 bags. Reaching 3,200 ppm in a 30 foot pool calls for 14 bags. With a 33 foot pool, figure on 15 to 18 bags.

Round poolAbout gallonsSalt to 3,200 ppm
12 ft × 48 in2,974Buy 2 bags · add 79 lb
12 ft × 52 in3,257Buy 3 bags · add 87 lb
12 ft × 54 in3,398Buy 3 bags · add 91 lb
15 ft × 48 in4,646Buy 4 bags · add 124 lb
15 ft × 52 in5,089Buy 4 bags · add 136 lb
15 ft × 54 in5,310Buy 4 bags · add 142 lb
18 ft × 48 in6,691Buy 5 bags · add 179 lb
18 ft × 52 in7,328Buy 5 bags · add 196 lb
18 ft × 54 in7,646Buy 6 bags · add 204 lb
21 ft × 48 in9,107Buy 7 bags · add 243 lb
21 ft × 52 in9,974Buy 7 bags · add 266 lb
21 ft × 54 in10,408Buy 7 bags · add 278 lb
24 ft × 48 in11,894Buy 8 bags · add 317 lb
24 ft × 52 in13,027Buy 9 bags · add 348 lb
24 ft × 54 in13,594Buy 10 bags · add 363 lb
27 ft × 48 in15,054Buy 10 bags · add 400 lb
27 ft × 52 in16,488Buy 11 bags · add 440 lb
27 ft × 54 in17,204Buy 12 bags · add 459 lb
30 ft × 48 in18,585Buy 13 bags · add 496 lb
30 ft × 52 in20,355Buy 14 bags · add 543 lb
30 ft × 54 in21,240Buy 15 bags · add 567 lb
33 ft × 48 in22,488Buy 15 bags · add 600 lb
33 ft × 52 in24,630Buy 17 bags · add 657 lb
33 ft × 54 in25,700Buy 18 bags · add 686 lb

Use Hayward's round-pool formula: diameter times diameter times water depth times 5.9 gives gallons, assuming the water sits 6 inches under the wall's top edge.

Figuring your pool's gallon count

Check how deep your water is before picking up any salt. Water at 48 inches means you're at 4 feet of depth. Take diameter times diameter times average depth times 5.9, the method shown in Hayward's manual.

According to the USGS, one gallon of water comes in at 8.34 pounds. Next, figure out how many pounds of salt that means. Multiply the gallons by 8.34. Multiply that figure by the ppm you're aiming for. Now divide the answer by 1,000,000. You'll usually find coarse solar salt sold in bags of 40 to 80 lb.

Intex plus other above ground setups

Certain units call for 3,000 ppm. Aim for 3,000 ppm using Intex's salt table, and the unit works anywhere from 2,500 to 3,500 ppm. Bestway's Flowclear, plus the Jandy TruClear, also ask for 3,000 ppm, which equals 3.0 gpl (grams per liter; 1 gpl is 1,000 ppm).

A higher figure comes from other manufacturers. The Hayward AquaRite covers 2,700 to 3,400 ppm, with the sweet spot at 3,200 ppm. A 3,500 ppm target applies to CircuPool, yet Pentair's guide asks for 3,600 ppm.

Questions people bring to the counter

How many 40lb salt bags does my pool need?

Starting from 0 ppm on a fresh fill, most round above ground pools take 2 to 18 bags, each holding 40 lb of salt. Getting a 15 foot pool to 3,200 ppm takes 3.5 to 4 bags, and a 30 foot one needs 14 bags. Once the salt goes in, let the pump run for 24 hours. After that, test before you add more.

What tells me my saltwater pool has enough salt in it?

Hold your salt reading up against the ideal range in your manual. Intex systems run best at 3,000 ppm, inside a 2,500 to 3,500 ppm band, while Hayward AquaRite asks for 2,700 to 3,400 ppm. Let the pump run for 24 hours once you've put the salt in, then test.

Is it possible to put too much salt in a salt water pool?

Yes, going past the ideal range for your unit can happen. The ceiling for Intex is 3,500 ppm, and Hayward caps its ideal band at 3,400 ppm. When you're above that, don't put in any more salt.

Does 4,000 PPM of salt count as too high for a pool?

For Intex and Hayward, a reading of 4,000 ppm is too high. The most Intex allows is 3,500 ppm. The top of Hayward's ideal band is 3,400 ppm. CircuPool advises keeping salt from 3,000 up to 4,000 ppm. A level of 4,000 ppm is where the SJ models work.

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