Free Online Calculators
Dose pH & chlorine for your pool volume
This calculator tells you exactly how much pH adjuster and chlorine to add based on your pool's volume and current water readings. It uses standard dosing guidelines to bring your water into the ideal range — pH 7.2–7.6 and a safe free chlorine level. No guesswork, no wasted chemicals, just a clean and balanced pool.
Start with your pool's water volume in gallons, then compare each measured reading (pH, free chlorine, total alkalinity, calcium hardness, cyanuric acid) against its target range. The dose is the gap between current and target multiplied by the volume and the strength of the product you are using.
There is no single best app — what matters is that the tool lets you enter your exact pool volume, your test results and the specific product strength you own. A web calculator that shows the dose per chemical works just as well as an app, since the underlying math is identical.
Aim for slightly alkaline pH, free chlorine in the recommended sanitizer range, balanced total alkalinity to keep pH stable, calcium hardness suited to your surface, and cyanuric acid high enough to protect chlorine from sunlight without stalling it. Balance them in order: alkalinity first, then pH, then sanitizer.
The dose depends on how far your pH and total alkalinity are above target and on the acid's concentration, so enter volume, current pH and alkalinity to get a figure. Add acid in portions, circulate, then retest before adding more.
The pH and total alkalinity crash, leaving water that is corrosive to plaster, grout, metal fittings, heaters and pump seals, and irritating to skin and eyes. You then have to raise pH and alkalinity back up with soda ash or sodium bicarbonate.
It scales with the volume and with how far pH and alkalinity sit above their targets, so the same pool needs very different amounts depending on the test results. Calculate the dose from your readings rather than using a fixed amount per pool size.
Only if the calculated dose for your volume and readings actually calls for that much — on a small pool it would drive the pH far too low. Split large doses across several additions with circulation and retesting in between.
Evening or early morning works best, with the pump running, so the acid disperses while nobody is swimming and sunlight is not driving off chlorine at the same time. Avoid dosing right before heavy bather use.
Adjust pH and alkalinity with acid first, then shock once the water has circulated and been retested. Chlorine works far more effectively at a balanced pH, and mixing the two products directly is dangerous.
Maintaining a clean, safe, and sparkling pool requires more than just running the pump. It demands precise chemical balance. Our free Pool Chemistry Calculator takes the guesswork out of dosing pH adjusters and chlorine for any pool volume. Whether you own a compact backyard pool or manage a larger swimming facility, this tool helps you achieve perfect water balance in seconds.
Pool water is a delicate chemical system. When the balance is off, the consequences range from mildly annoying to genuinely dangerous. Too much chlorine causes eye and skin irritation; too little allows bacteria, viruses, and algae to thrive. An incorrect pH level renders chlorine ineffective and can degrade pool surfaces, liners, and equipment over time.
The ideal pH range for a swimming pool is 7.2 to 7.6, with 7.4 being the sweet spot. Free chlorine should be maintained between 1.0 and 3.0 ppm for most residential pools. Achieving these targets requires knowing exactly how much chemical product to add based on your pool's specific water volume — and that's precisely what this calculator does.
Using the calculator is straightforward. Simply enter the following information:
The calculator instantly tells you how much pH decreaser (e.g., sodium bisulfate) or pH increaser (e.g., sodium carbonate) to add, and how much chlorine granulate or tablets you need. Results are displayed in grams or kilograms, making it easy to measure and apply the right amount without waste.
Imagine your pool holds 20,000 liters. After a sunny weekend with several swimmers, you test the water and find a pH of 7.9 and a chlorine level of 0.5 ppm — both out of range. You want to bring the pH down to 7.4 and raise chlorine to 1.5 ppm.
Entering these values into our Pool Chemistry Calculator gives you specific dosage recommendations — for example, approximately 180 grams of pH minus and 60 grams of 65% active chlorine granulate. This precision prevents the common mistake of over-treating the water, which wastes money and can make swimming uncomfortable or even unsafe.
Consistency is key when it comes to pool maintenance. Here's a recommended testing schedule:
Regular testing paired with accurate dosing using our calculator keeps your pool consistently clean, clear, and safe for everyone.
While pH and chlorine are the most critical daily parameters, a truly well-maintained pool also considers total alkalinity (which buffers pH), calcium hardness (to prevent scaling or corrosion), and cyanuric acid (a stabilizer that protects chlorine from UV degradation in outdoor pools).
Our calculator focuses on the two most immediate and impactful variables — pH and chlorine — giving you actionable results without overwhelming complexity. For comprehensive water testing, we recommend using a full-spectrum test kit alongside this calculator.
For a rectangular pool, multiply length × width × average depth to get cubic meters (then multiply by 1,000 for liters). For round or oval pools, use the appropriate geometric formula. Many pool chemistry calculators, including ours, allow you to input dimensions directly to compute volume automatically.
This depends on pool usage, sunlight exposure, and temperature. During hot, busy summer days, daily top-ups may be necessary. Using slow-dissolving chlorine tablets in a floater can help maintain a steady baseline level between treatments.
Over-chlorination causes red eyes, skin irritation, and bleaching of swimwear. It can also damage pool surfaces over time. If chlorine levels exceed 5 ppm, avoid swimming and allow the water to off-gas naturally or use a chlorine neutralizer. Our calculator helps prevent this situation entirely.
Absolutely. The calculator is 100% free, requires no registration or account, and runs entirely in your browser. You can use it as often as needed throughout the swimming season.
The same chemical principles apply to hot tubs, though target ranges differ slightly. Hot tubs require higher chlorine levels (3–5 ppm) due to their smaller volume and higher temperatures, which accelerate chemical consumption. Adjust the target values accordingly when using the calculator for spas.