Pool Salt Calculator
Find how many pounds of salt a saltwater pool needs to reach its target salinity.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
Estimate salt mass from pool volume and the current and target salinity you enter. The result is an amount of salt, not product dosing advice. Confirm the target range in your salt-system manual and retest after adding in stages.
Worked example
calculated with the default values below
Pool volume 15,000 gal · Current salt level 2,200 ppm · Target salt level 3,200 ppm · Salt bag size 40 lb Salt to add 125.0 lb · Salt to add 56.7 kg · Bags to buy 4 · Note Add in two or three doses with the pump running so the salt dissolves evenly
Method and assumptions
S_lb = G × max(0, ppm_t − ppm) ÷ 120000; bags = ceil(S_lb ÷ s) kg = lb × 0.45359237; bags rounded up (default 40 lb). Estimate salt mass from pool volume and the current and target salinity you enter. The result is an amount of salt, not product dosing advice. Confirm the target range in your salt-system manual and retest after adding in stages. Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data.
Data sources
Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data.
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
S_lb = G × max(0, ppm_t − ppm) ÷ 120000; bags = ceil(S_lb ÷ s)
- S_lb
- Salt needed (lb)
- G
- Pool volume (gal)
- ppm_t
- Target salt (ppm)
- s
- Source unit code
- bags
- Bags to buy
- ppm
- Current salt level (ppm)
kg = lb × 0.45359237; bags rounded up (default 40 lb).
Frequently asked questions
Why does the salt formula divide ppm difference by 120,000?
The tool converts the entered ppm difference to salt mass: pool gallons × ppm difference ÷ 120,000. For 15,000 US gallons going from 2,200 to 3,200 ppm, that is 125 lb (about 56.7 kg). With 40 lb bags, the estimate is 3.125 bags, so you would need 4 whole bags. Check your system manual and add in stages.
Which inputs and limits apply to Pool Salt Calculator?
Use the units shown beside each field. These are form limits, not recommended settings. Pool volume: 100–200,000 gal; Current salt level: 0–6,000 ppm; Target salt level: 2,000–5,000 ppm; Salt bag size: 10–100 lb S_lb = G × max(0, ppm_t − ppm) ÷ 120000; bags = ceil(S_lb ÷ s) kg = lb × 0.45359237; bags rounded up (default 40 lb). Estimate salt mass from pool volume and the current and target salinity you enter. The result is an amount of salt, not product dosing advice. Confirm the target range in your salt-system manual and retest after adding in stages. Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data.
What is a complete worked example for Pool volume = 15,000 gal; Current salt level = 2,200 ppm?
Inputs: Pool volume = 15,000 gal; Current salt level = 2,200 ppm; Target salt level = 3,200 ppm; Salt bag size = 40 lb. Calculation: S_lb = G × max(0, ppm_t − ppm) ÷ 120000; bags = ceil(S_lb ÷ s). Results: Salt to add = 125.0 lb; Salt to add = 56.7 kg; Bags to buy = 4; Note = Add in two or three doses with the pump running so the salt dissolves evenly.