Salt dosage calculator: how much salt for your chlorinator?
Most salt chlorinators run at around 4 g/L of salt (4,000 ppm). Enter the volume, the measured level and the target level to find the exact amount to add — since salt does not evaporate, it only needs topping up after dilution.
Result
Salt to add200kg
That is about8bags of 25 kg
Pour the salt directly into the pool (never into the skimmers), with filtration running, and wait for it to dissolve fully (24 to 48 h) before restarting the chlorinator.
Use a dedicated pool salt; avoid iodised or anti-caking table salt.
How this calculation works
This calculation applies the dilution rule used by professionals:
Salt to add (kg) = Volume (m³) × (target level − measured level), in g/L.
The units line up directly: 1 g/L equals 1 kg/m³. To bring water from 2.5 to 4 g/L in a 50 m³ pool, you therefore need 50 × (4 − 2.5) = 75 kg of salt. Since salt is not consumed, this top-up is only needed after a partial drain, winterisation or heavy rain.
Salt for a fresh pool (0 → 4 g/L):
| Volume | Salt to add | 25 kg bags |
|---|---|---|
| 20 m³ (20,000 L) | 80 kg | 4 bags |
| 30 m³ (30,000 L) | 120 kg | 5 bags |
| 40 m³ (40,000 L) | 160 kg | 7 bags |
| 50 m³ (50,000 L) | 200 kg | 8 bags |
| 60 m³ (60,000 L) | 240 kg | 10 bags |
These figures assume fresh water taken to 4 g/L. For a top-up, enter your measured level above: the calculator only counts the gap.
Frequently asked questions
How many bags of salt for a 50,000 litre pool?
For a fresh pool brought to 4 g/L, that is about 200 kg — eight 25 kg bags — for 50,000 L, i.e. 4 kg per m³. For a top-up, multiply the volume in m³ by the gap between your target and measured level; the calculator above does it exactly for your case.
How do I measure the salt concentration?
Three ways: a dedicated salt test strip, an electronic salinity tester (the most accurate), or the chlorinator’s own display, which reads the measured level. Always measure before adding salt, and never just after rain or a recent addition.
g/L or ppm — what is the difference?
It is the same measurement written differently: 1 g/L = 1,000 ppm. A chlorinator set to 4 g/L therefore means 4,000 ppm. Check the unit your device shows so you do not aim ten times too high or too low.
What salt level should a chlorinator have?
The common range is 3 to 7 g/L, but most chlorinators are optimised around 4 g/L. Always refer to the value stated by your unit’s manufacturer.
Does salt get used up over time?
No. Electrolysis turns salt into chlorine, which then recombines into salt: the level stays stable. It only drops through dilution (rain, partial drain, splash-out, winterisation).
Which salt should I use?
A dedicated pool salt, low in impurities. Avoid table salt, which is often iodised or treated with anti-caking agents that can cloud the water or damage the cell.