Pool Chemical Calculator
Pool Balance's pool chemical calculator turns your water test into a clear, step-by-step dosing plan. Enter your pool volume and your current readings for free chlorine, pH, total alkalinity, calcium hardness and cyanuric acid (CYA), and the calculator tells you which levels are off and exactly how much of each chemical to add to reach the recommended range.
Never mix different pool chemicals directly with each other — especially chlorine products with acid, which can produce toxic gas. Always add chemicals to the water, never water to chemicals, wear gloves and eye protection, and handle chemicals in a well-ventilated area without breathing fumes.
Accurate dosing matters because pool chemistry is connected. pH controls how well chlorine works — at pH 7.5 only about half of your chlorine is actively working, and at pH 8.0 that drops to roughly a quarter. Alkalinity buffers pH, so when it's low, pH swings around; when it's high, pH keeps drifting up. Calcium hardness protects plaster and equipment from etching or scale, and CYA shields chlorine from sunlight but also changes how much chlorine you need. Guessing "a cup or two" of one product often knocks another level out of range, which wastes chemicals, money and swim days.
This pool chemistry calculator works from your actual pool size, so a 12,000-gallon above-ground pool and a 30,000-gallon in-ground pool get different, sensible amounts. Don't know your volume? Use the built-in pool volume helper with your length, width or diameter and depth.
For best results, test in the morning before the sun burns off chlorine, adjust one chemical at a time with the pump running, and retest before adding the next. Always check the concentration on your product label — amounts vary by product strength, pool surface, water temperature and CYA level. Your first three pool tests are free.
Pool chemical calculator FAQ
How much chlorine do I need for my pool?
It depends on your pool volume, current free chlorine and target. As a rule of thumb, about 10 fl oz of 10% liquid chlorine per 10,000 gallons raises free chlorine by about 1 ppm. For example, raising a 30,000-gallon pool from 0.8 to about 2.5 ppm takes approximately 51 fl oz of 10% liquid chlorine, or about 10 oz of 65% cal-hypo. The calculator does this math for your exact pool.
What chemical levels should a pool have?
Common targets are pH 7.2–7.6 and total alkalinity 80–120 ppm, with free chlorine kept in range for your CYA level. The calculator flags each reading as low, ideal or high and shows what to add.
Which chemical should I adjust first?
Adjust alkalinity and pH before chlorine, one product at a time. Soda ash raises pH and nudges alkalinity up too, so add it first, circulate 4–6 hours, then retest before finalizing your baking soda dose. That order applies when pH and alkalinity are low — if they're high instead, the steps reverse.
Related: lowering high pool pH
How do I find my pool's volume in gallons?
Multiply length × width × average depth × 7.5 for a rectangular pool, or use the calculator's pool volume helper, which also handles round and oval pools.
Is the pool chemical calculator free?
Yes. Your first three pool tests are free with no trial or card required. Pool Pro unlocks unlimited tests and extra tools.