Pool & spa
Pool Saltwater Calculator
Works out a salt system conversion, which changes how the pool is maintained rather than removing chemistry.
Result
Dose against a test result, never against a schedule. Add chemicals in stages with the pump running, wait for a full turnover, then retest before adding more. Never mix chemicals, and never add water to acid. Where a product label differs from the figure here, the label wins. Use salt sold for pools: it dissolves cleanly and carries no anti-caking additives or iron that would stain the surfaces. Brush it across the floor rather than letting it pile up, and run the pump for a full turnover before testing.
Get a Free Business AuditHow the calculation works
Converting to a salt system means the initial salt charge, which is the target salinity times the volume, plus the generator and cell installation. The calculation covers the salt and the dose, and the operating reality is what matters: the system produces chlorine continuously from dissolved salt, which removes the chore of adding chlorine but does not remove the need to test and manage pH, alkalinity, calcium and stabiliser. A salt pool is a chlorine pool with a different delivery method.
What moves the number
- Volume, which sets the initial salt charge.
- Cell sizing against the pool volume, since an undersized cell runs constantly.
- Whether existing fittings and surfaces tolerate salinity.
- Cell replacement cost and expected life, which is the recurring cost.
Where this one goes wrong
Salt systems are not chemical-free and are frequently sold as though they were. They produce chlorine, so the water is chlorinated, and pH, alkalinity, calcium hardness and stabiliser all still need testing and adjusting. They also drive pH upward as a side effect of generation, so acid demand is typically higher than on a traditional pool rather than lower. The cell is a consumable with a finite life and a meaningful replacement cost, which is the honest recurring figure to set against saved chlorine purchases. Salinity also accelerates corrosion of some metal and stone components, which is worth checking before converting.
Before you quote
- Set expectations that a salt pool still needs full chemistry management.
- Price cell replacement into the running cost comparison.
- Check metal fittings and stone coping for salt tolerance.
- Size the cell to the volume so it is not running constantly.
Where the rules come from
Questions
About this calculator
Is a saltwater pool chlorine-free?
No. It generates chlorine from dissolved salt rather than having chlorine added, so the water is chlorinated. pH, alkalinity, calcium and stabiliser all still need testing and adjusting, and generation drives pH upward so acid demand is usually higher rather than lower.
What does a salt system actually cost to run?
The honest figure includes the cell, which is a consumable with a finite life and a meaningful replacement cost. Set against saved chlorine purchases, the saving is real but smaller than it first appears. Salt itself is cheap and only replaces what leaves with water.
Will salt damage my pool?
Salinity accelerates corrosion of some metal fittings, ladders, handrails and certain stone copings, and it is worth checking what the pool has before converting. The salinity of a pool is far below seawater, but it is enough to matter for susceptible materials over years.
The formula
about 8.35 lb of salt per 10,000 gallons raises salinity 100 ppm
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How to use this calculator
- Pool volume (gallons). Enter your own figure; the page starts at 20,000.
- Current salt (ppm). Enter your own figure; the page starts at 0.
- Target salt (ppm). Enter your own figure; the page starts at 3,200.
- Price per pound or gallon ($). Enter your own figure; the page starts at $0.22.
The result updates as you type, so you can try a figure, see what it does to salt to add, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Pool volume (gallons) | 20,000 |
| Current salt (ppm) | 0 |
| Target salt (ppm) | 3,200 |
| Price per pound or gallon | $0.22 |
What comes out
| Result | Value |
|---|---|
| Salt to add main result | 534.4 |
| Change needed | 3,200.0 |
| Estimated cost | $117.57 |
| Dose per 10,000 gallons | 267.2 |
Add about 534.4 to move 20,000 gallons from 0 to 3200.
How sensitive the answer is
Holding everything else steady and changing only price per pound or gallon, this is what happens to salt to add. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Price per pound or gallon ($) | Salt to add |
|---|---|
| $0.11 | 534.4 |
| $0.17 | 534.4 |
| $0.22 example above | 534.4 |
| $0.33 | 534.4 |
| $0.44 | 534.4 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Pool volume (gallons)
- A number, between 0 and 2000000, starting at 20,000.
- Current salt (ppm)
- A number, between 0 and 6000, starting at 0.
- Target salt (ppm)
- A number, between 0 and 6000, starting at 3,200.
- Price per pound or gallon ($)
- A money amount, starting at $0.22.
What the results tell you
| Result | What it is |
|---|---|
| Salt to add | The headline result. A decimal figure. |
| Change needed | A decimal figure. |
| Estimated cost | A money figure. |
| Dose per 10,000 gallons | A decimal figure. |
Estimating is the easy part
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