Pool Salt Calculator
0 for a freshly filled pool.
From your salt cell's manual.
Salt to add
401 lb
Add 401 lb of pool salt (11 bags of 40 lb) to raise 15,000 gallons from 0 to 3,200 ppm.
- Increase
- 3,200 ppm
- Bags
- 11 × 40 lb
- Rate
- 83.5 lb per 10,000 gal per 1,000 ppm
- Never mix pool chemicals with each other, wet or dry.
- Always add chemicals to water, never water to chemicals.
- Follow the manufacturer's label. It overrides any calculator, including this one.
How it's calculated
Salt concentration is measured in ppm, which equals milligrams per liter. Multiply the increase by the number of liters and convert milligrams to pounds:
A shortcut that gives the same answer: a US gallon of water weighs 8.345 lb, so each 1 ppm in 1,000,000 gallons is 8.345 lb of salt. For 10,000 gallons that is 0.0835 lb per ppm, or about 83.5 lb per 1,000 ppm. If the pool already has more salt than the target, the calculator shows the share of water to replace: (current − target) ÷ current.
Worked example
A new 15,000 gallon pool filled with tap water (0 ppm) and a cell that wants 3,200 ppm:
- Volume in liters: 15,000 × 3.785 = 56,781 L.
- Salt needed: 3,200 × 56,781 = 181,699,776 mg.
- In pounds: 181,699,776 ÷ 453,592 = 401 lb (182 kg).
- In 40 lb bags: 401 ÷ 40 = 10 → 11 bags.
Unless the pool is brand new, add about three-quarters of the dose, let it dissolve for a day and retest with salt strips or a meter before adding the rest. Salt readings from the cell itself can drift, so confirm with a separate test.
How to add salt
- Turn the salt cell off (the pump stays on).
- Spread the salt around the shallow end and along the walls, away from the skimmer.
- Brush any salt on the floor toward the main drain.
- Run the pump for 24 hours, retest, then switch the cell back on.
Pool salt by pool size
| Pool size | 0 → 3,200 ppm | 40 lb bags | Per +500 ppm |
|---|---|---|---|
| 10,000 gal | 267 lb | 7 | 42 lb |
| 15,000 gal | 401 lb | 11 | 63 lb |
| 20,000 gal | 534 lb | 14 | 83 lb |
| 25,000 gal | 668 lb | 17 | 104 lb |
| 30,000 gal | 801 lb | 21 | 125 lb |
Pool salt is most commonly sold in 40 lb bags in the US (20 or 25 kg elsewhere).
Frequently asked questions
How many bags of salt do I need for a 15,000 gallon pool?
Starting from fresh water, reaching 3,200 ppm takes about 401 lb of salt, or 11 bags of 40 lb. Topping up from 2,700 to 3,200 ppm takes about 63 lb (2 bags).
What salt level should a saltwater pool have?
Most chlorine generators want 3,000–3,200 ppm, and work in roughly 2,700–3,400 ppm. The exact range is printed in your cell's manual and often on the control panel. Below the range the cell makes less chlorine or shuts off; far above it, it may flag an error.
What happens if I add too much salt?
A little extra is harmless. Much too much can trigger a high-salt error on the generator and taste noticeably salty. Salt does not evaporate, so the only way to lower it is to drain part of the water and refill with fresh water; the calculator tells you how much.
How long does pool salt take to dissolve?
Fine pool salt usually dissolves within a day with the pump running. Brush undissolved salt off the floor toward the main drain to speed it up, and wait about 24 hours before trusting a salt reading.
Does salt level go down over time?
Salt only leaves with water that leaves the pool: splash-out, backwashing, draining and rain overflow. Evaporation removes water but not salt. That is why salt levels drop slowly over a season and usually need a bag or two to top up.
What kind of salt should I use in a pool?
Use salt sold for pools or, failing that, plain sodium chloride of at least 99% purity with no anti-caking agents, iodine or additives. Rock salt and water-softener pellets with additives can stain or cloud the water.
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