Balance pool and hot tub water with exact doses
Enter your test and the products you own. You get exact amounts, in the order to add them, for pools and hot tubs.
Test, dose, swim: the 30-second calculator
Example: for a 15,000-gallon pool at 1 ppm chlorine, pH 7.8, alkalinity 70, and stabilizer 40, the plan is 58 fl oz of 10% liquid chlorine, then 4.2 lb of baking soda, then about 13 fl oz of muriatic acid. It works for pools from 100 gallons and hot tubs from 50. No account is needed, and nothing leaves your browser.
The calculator above reads four numbers from any test strip or drop kit: free chlorine (FC), pH, total alkalinity (TA), and stabilizer (CYA). It returns a numbered plan: what to add, how much of your bottle, and what to do between steps. Three things change every dose, so the calculator always asks for them:
- Product strength. A jug of 12.5% liquid chlorine and a bottle of 6% bleach need very different amounts for the same result.
- Stabilizer (CYA). The more CYA in the water, the more free chlorine you need. At 40 ppm CYA, the minimum FC is 3 ppm, not 1.
- Pool size. Every dose scales with gallons. If you're not sure, use the pool volume calculator first.
The order follows the usual rule: chlorine first if it is below the minimum, then alkalinity, then pH. Big corrections are split into steps (for example, no more than 0.4 pH at a time with acid), so you never "dump the whole bag". Need calcium, salt, or combined chlorine too? Use the full pool chemical calculator.
Popular calculators
- How much chlorine to add for liquid chlorine, bleach, cal-hypo, dichlor, or trichlor, and the liquid chlorine calculator for weak or aging jugs.
- Chlorine tablets per week from your own daily chlorine loss, with the stabilizer they add.
- Raise pH with soda ash, and muriatic acid to lower it, rounded down on purpose.
- Raise alkalinity with baking soda, up to 30 ppm at a time, or lower it with acid and aeration.
- Pool salt in pounds and 40 lb bags for salt water pools.
- Dose charts by product and pool size, and every target level on the pool chemical chart.
Fix a problem: green, cloudy, chlorine won't hold
Most water problems come down to chlorine that is too low for your stabilizer level. Green water means algae has taken hold: clearing it takes a shock dosed by your product's label, brushing, and several days of filtering. Cloudy water is usually low chlorine, high pH, or a filter that can't keep up. If chlorine disappears overnight, see why chlorine isn't holding. Every problem page starts with a short diagnosis and ends with a dose for your pool.
Hot tub corner
A hot tub is not a small pool. It runs hotter, holds far more bathers per gallon, and needs more sanitizer. The CDC recommends at least 3 ppm free chlorine or 4 ppm bromine, and no stabilizer. The calculators in our hot tub section work from 50 to 1,500 gallons and show small doses in teaspoons and grams, so you don't have to guess with a pool-sized scoop.
Above-ground and Intex pools
The size on the box is not how much water your pool holds. We compared 26 above-ground pools whose makers state a fill level: the median model holds 0.933 times the volume its nominal size suggests, and some inflatable-ring pools hold as little as 0.823. For example, an Intex Easy Set 18 ft × 48 in is rated at 5,455 gallons, while simple geometry for that size and fill gives about 6,091. Start in the above-ground section or look up your model in the above-ground pool gallons chart.
Why our numbers match Taylor and PHTA
Every number on this site comes from one set of published formulas, the same one the app uses. We check it against independent references before each release. A few examples for a 10,000-gallon pool:
| Dose | Our engine | Reference |
|---|---|---|
| +1 ppm FC, 10% liquid chlorine | 12.8 fl oz | 12.8 fl oz (Taylor K-1005 table) |
| +10 ppm TA, baking soda | 1.40 lb | 1.40 lb (Taylor) |
| Salt 0 → 3,200 ppm | 267 lb | 267 lb (Hayward) |
The full list of formulas, constants, sources, and the 67 test cases is on our methodology page. For target ranges at a glance, see the pool chemistry chart.
Safety first
Never mix chlorine and acid, even in an empty bucket. Add chemicals to water, not water to chemicals, one product at a time with the pump running. Pool chemicals send thousands of people to U.S. emergency rooms every year, according to the CDC. Always follow the product label.
Get the app: save your pool, log tests, see trends
The site answers "How much do I add today?" The Pooldex app for iPhone remembers your pool and your products, keeps a test log with charts, and reminds you when to test again. No account is needed. Your data stays on your iPhone and in your iCloud.