Pool Salt Calculator: How Much Salt Do I Add?
Answers: how much salt do I add?
Pool & Spa
Pool volume, salt dosing and target chemical levels, with the math shown and your pool’s size built in.
- 8 guides
- 2 tools
- 3 topics
- Reviewed Oct 3, 2026
Set your ZIP to see dates for your area.
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Pool & Spa, one topic at a time
Water chemistry
Target levels for chlorine, pH, alkalinity, calcium and stabilizer, how much shock to add, and how salt pools… 3 guides
Opening & closing
When to open your pool in spring and close it for winter, timed to your local climate, and… 2 guides
Hot tubs
Hot tub water chemistry from CDC and state spa codes, what a tub costs to keep hot where… 3 guides
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Pool & Spa tools
Pool Volume Calculator: How Many Gallons Is My Pool?
Answers: how many gallons is my pool?
The pool & spa year
What to do, month by month
Typical timing for most of the US, starting this month. Set your ZIP and the guides shift every date to your frost dates.
- NovNow Keep the hot tub full, hot and covered Most owner’s manuals keep a tub running all winter; drain it only if it will sit unused through hard freezes.
- Jan Note your pool’s gallons Every chemical dose is per gallon, so start with the volume.
- Mar Work out the opening salt dose Test first: most pools already hold some salt.
- Apr Test salt with two methods Readings vary by several hundred ppm, and extra salt only comes out by draining.
- May Measure the pool’s volume Use the water depth, not the wall height.
- Jun Retest salt after big storms Pumping off an inch of rain lowers salt about 52 ppm in a 5-ft-deep pool.
- Jul Find your wettest swim month Save your ZIP code and the salt calculator shows it.
- Aug Start checking a pool thermometer Close when the water stays below about 65°F for several days.
- Sep Close before freezing nights Water left in pipes, the pump or the filter can freeze and crack them.
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This month for your pool & spa
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Pool & Spa How-to
Calculator
How to Winterize a Hot Tub, and When to Keep It Running
Hot tub makers say a tub kept full, heated and covered protects itself from freezing. When to drain and winterize instead, with NOAA freeze dates and winter running costs for 21 US cities.
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Pool & Spa Guide
Calculator
How Much Does It Cost to Run a Hot Tub? The Math by City
The median hot tub certified in California costs about $25 a month to keep hot at the US average electricity price. Standby cost by month for 21 cities from CEC test data, NOAA normals and EIA prices.
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Pool & Spa Guide
Calculator
Hot Tub Chemical Levels: Chlorine, Bromine and pH Ranges by Source
CDC’s hot tub minimums are at least 3 ppm free chlorine or 4 ppm bromine, pH 7.0–7.8, no stabilizer and water no hotter than 104°F. Three state spa codes and three spa manuals compared, plus testing and refill schedules.
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Pool & Spa How-to
Calculator
How to Winterize a Hot Tub, and When to Keep It Running
Hot tub makers say a tub kept full, heated and covered protects itself from freezing. When to drain and winterize instead, with NOAA freeze dates and winter running costs for 21 US cities.
Pool & Spa Guide
Calculator
How Much Does It Cost to Run a Hot Tub? The Math by City
The median hot tub certified in California costs about $25 a month to keep hot at the US average electricity price. Standby cost by month for 21 cities from CEC test data, NOAA normals and EIA prices.
Pool & Spa Guide
Calculator
Hot Tub Chemical Levels: Chlorine, Bromine and pH Ranges by Source
CDC’s hot tub minimums are at least 3 ppm free chlorine or 4 ppm bromine, pH 7.0–7.8, no stabilizer and water no hotter than 104°F. Three state spa codes and three spa manuals compared, plus testing and refill schedules.
Pool & Spa Seasonal
Calculator
When to Open Your Pool: Estimated Dates for Your City and State
Open before the water warms past 60°F and after freezing nights end. Estimated opening dates for 49 cities from NOAA climate normals, and how the 70°F rule compares.
Pool & Spa Comparison
Calculator
Saltwater vs Chlorine Pool: What Changes and What It Costs
A saltwater pool is a chlorine pool: a salt cell makes the chlorine. Cell electricity and wear per gallon of liquid chlorine replaced, upkeep and corrosion from the manuals, and the stabilizer tablets add in 19 US cities.
Pool & Spa How-to
Calculator
How Much Shock to Add to a Pool: Doses, SLAM and CYA
One label shock dose adds about 5–10 ppm free chlorine. Label doses for liquid chlorine, cal-hypo, dichlor and non-chlorine shock, SLAM levels by stabilizer, and the CYA that weekly dichlor adds by city.
Pool & Spa Guide
Calculator
Ideal Pool Chemical Levels: The Ranges and Who Sets Them
Free chlorine 2–3 ppm, pH 7.4–7.6, alkalinity 80–120 ppm, calcium 200–400 ppm, stabilizer 30–50 ppm: every range tied to CDC or a manufacturer’s manual.
Pool & Spa Seasonal
When to Close Your Pool: Estimated Dates for Your City and State
Close once the water stays below 65°F, or 60°F to be safer, and before freezing nights. Estimated dates for 46 cities from NOAA climate normals.
About this section
How we cover pool & spa
Most pool problems start with a guess: a dose added without knowing the volume, or salt added from a single test reading. Pentair, for one, rates its own salt sensor at ±500 ppm. Our calculators turn your pool’s size and today’s reading into a dose, checked against the manufacturers’ own charts, and the guides explain what each number protects you from.
We show the formula with every result and repeat the rules that matter most: test first, follow the label and the manufacturer’s manual, and never mix products. Seasonal guides use NOAA temperature and rainfall normals for your ZIP instead of a fixed calendar.
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Seasonal reminders for your ZIP
Get a short email when it’s time to overseed, start seeds, open the pool or service your furnace — timed to your climate.
Check your inbox to confirm. Your first reminder will arrive when it’s time.