Pool Salt Calculator
Enter your pool volume, current salt reading, and target concentration. The calculator tells you how many pounds (or kilograms) of salt to add, or how many gallons (or litres) of water to replace if you are over the target. An optional bag count and cost estimate helps you plan your next trip to the store. Results update instantly as you type.
How to calculate how much salt to add to a pool
The core formula is straightforward: salt to add (lb) = pool volume (gal) x 0.000008345 x ppm deficit. The constant comes from the definition of ppm and the density of water. In metric units, it simplifies to: salt to add (kg) = pool volume (L) x 0.000001 x ppm deficit, because 1 ppm is exactly 1 mg per litre, and 1 kg = 1,000,000 mg. For example, a 15,000-gallon pool starting at 0 ppm and targeting 3,200 ppm needs 15,000 x 0.000008345 x 3,200 = about 401 lb of salt. If you are over-target, you cannot remove dissolved salt directly: you drain a fraction of the pool and refill with fresh water. The drain fraction is 1 minus (target ppm divided by current ppm).
Why salt level matters for your saltwater pool system
A salt-chlorine generator (SWG) works by passing an electrical current through slightly salty water, splitting sodium chloride into hypochlorous acid (the same sanitiser as liquid chlorine). If the salt is too low, the cell does not produce enough chlorine and most generators shut down with a low-salt alarm. Running a cell under-salted shortens its life, because it draws more current to compensate. If the salt is too high, the water becomes corrosive and the SWG runs inefficiently. The ideal window for most generators is 2,700 to 3,400 ppm, with 3,200 ppm widely cited as the optimum. Always check your generator manual: some brands specify a tighter or slightly different range. Unlike chlorine, salt does not evaporate, so concentrations only drop through splash-out, backwashing, heavy rain dilution, or filter cleaning.
Choosing the right pool salt and adding it safely
Always use pool-grade or food-grade sodium chloride that is at least 99.8% pure NaCl. Avoid rock salt (often contains dirt and clay), table salt with iodine or anti-caking additives (both can stain pool surfaces and damage equipment), and solar salt with yellow prussiate of soda (an anti-caking agent). When adding salt, pour it directly into the pool around the perimeter with the pump and filter running at full circulation. Brush the salt immediately to help it dissolve and prevent it from settling on the floor and etching the surface. Never pour salt into the skimmer basket, as a concentrated slug of brine can damage the SWG cell. Wait 24 hours before re-testing to allow the salt to fully mix and the reading to stabilise.
How to reduce salt that is too high
If your pool salt level is above target, the only practical solution is dilution: drain a portion of the pool and replace it with fresh water. The calculator shows exactly how many gallons (or litres) to drain. For example, to bring a 15,000-gallon pool from 4,000 ppm down to 3,200 ppm, you need to drain about 3,000 gallons (20%) and refill. After refilling, run the pump for several hours and re-test before making any further adjustments. If the reading is still high, repeat the drain-and-refill cycle in smaller steps rather than draining a large volume at once.
Saltwater pool salt level guide
| Salt level (ppm) | Status | SWG effect |
|---|---|---|
| Below 2700 | Too low | SWG may shut off or underproduce chlorine |
| 2700-3000 | Low end of acceptable | Reduced chlorine output; watch closely |
| 3000-3400 | Ideal range | Optimal chlorine production; generator runs efficiently |
| 3400-4000 | Slightly high | SWG still functions; corrosion risk begins to rise |
| Above 4000 | Too high | SWG alarms, reduced efficiency, corrosion accelerates |
Recommended salt concentrations and the effect on your salt-chlorine generator (SWG).
Frequently asked questions
What is the ideal salt level for a saltwater pool?
Most salt-chlorine generators work best between 2,700 and 3,400 ppm, with 3,200 ppm considered the widely accepted ideal. However, always check your specific generator manual, as some brands call for 3,000 ppm or 3,500 ppm. Staying within the manufacturer range protects the cell and ensures consistent chlorine production.
How often should I test my pool salt level?
Test the salt level at the start of each swimming season, after heavy rain or flooding, after backwashing or cleaning the filter, and any time your SWG shows a low-salt alarm. A general rule is to test every 2-4 weeks during the swim season. Salt does not evaporate but is gradually lost through splash-out, backwash, and dilution from rain.
Can I use regular table salt in my pool?
No. Table salt typically contains iodine and anti-caking agents (such as sodium ferrocyanide or calcium silicate) that can stain pool surfaces, cloud the water, and damage salt-cell electrodes over time. Use pool-grade or food-grade sodium chloride that is at least 99.8% pure NaCl with no additives.
My pool salt is too high. What do I do?
Salt cannot be chemically neutralised in a pool. The only remedy is dilution: drain a portion of the pool and refill with fresh water. This calculator shows exactly how much water to drain. After refilling and running the pump for several hours, re-test before deciding whether a second dilution is needed.
Does salt level affect pH or other water chemistry?
Salt itself has little direct effect on pH. However, the chlorine generated by a SWG produces slightly acidic byproducts, so saltwater pools often experience a slow rise in pH over time. Regularly testing and adjusting pH (ideal: 7.4-7.6), alkalinity (80-120 ppm), and cyanuric acid (stabiliser, 70-80 ppm for SWG pools) is just as important as maintaining salt level.
How long after adding salt can I swim?
You can typically swim about 30 minutes after adding salt, as long as the salt is fully dissolved and the pump is running. The salt itself is not harmful at pool concentrations, which are far below seawater. However, wait 24 hours before re-testing the salt level, because the reading will not be accurate until the salt is fully mixed throughout the pool.