Pool Chlorine Calculator
Estimate how much chlorine is required to raise and maintain sanitizing free chlorine levels in your pool water.
Pool Parameters
Skip measurements and enter gallons directly
Triples the required chemical chlorine shock dosage
Water Volume
0 Gal
Total pool water capacity
Salt Required
0 Lbs
0 bags (40 lb bags)
Shock Chlorine
0 Lbs
Calcium Hypochlorite dose
Pool Geometry Outline
Maintaining Sanitizing Chlorine Levels in Swimming Pools
Chlorine is the primary sanitizing chemical used in both traditional and saltwater swimming pools. It works by oxidizing organic compounds and destroying bacteria, viruses, and algae cells on contact. To ensure your pool water remains safe and sanitary, you must maintain a constant **free chlorine level of 1.0 to 3.0 PPM**.
Unlike a shock treatment which raises chlorine levels to hyperchlorinate water temporarily, daily maintenance requires adding smaller dosages of stabilized tablets, granular chlorine (dichlor), or unstabilized liquid chlorine to replace chlorine that has been burned off by sunlight or consumed during sanitization.
The Role of Stabilizers (Cyanuric Acid)
Unstabilized chlorine is highly sensitive to ultraviolet (UV) radiation from sunlight. Without a stabilizer, UV rays can destroy up to 90% of your pool's free chlorine in less than two hours. To prevent this, pool owners add **Cyanuric Acid (CYA)**, which binds to free chlorine and shields it from UV damage.
- Optimal CYA Level: Keep CYA between 30 and 50 PPM.
- Chlorine Lock: If CYA exceeds 100 PPM, it binds to chlorine too tightly, rendering it inactive. The only way to lower CYA levels is to drain and refill a portion of the pool.
Dosage Guidelines
On a typical 15,000-gallon pool, adding 10 fluid ounces of liquid chlorine (12.5% strength) raises the free chlorine level by approximately 1 PPM. Granular dichlor raises free chlorine and stabilizer levels simultaneously. Use this calculator to estimate the volume capacity of your pool to ensure precise daily chlorine additions.
Chlorine FAQs
What is the difference between free chlorine and combined chlorine?
Free chlorine is the active, unused chlorine available to sanitize your pool water. Combined chlorine is chlorine that has already reacted with contaminants, forming chloramines. You want to maintain free chlorine between 1 and 3 PPM and keep combined chlorine below 0.5 PPM.
How does cyanuric acid affect pool chlorine?
Cyanuric acid (CYA) acts as a sunscreen for chlorine, stabilizing it and preventing it from burning off under UV sun rays. However, if CYA levels get too high (above 50-60 PPM), it binds to chlorine too tightly, reducing its sanitizing efficiency. Keep CYA balanced between 30 and 50 PPM.
Should I use chlorine tablets or liquid chlorine?
Chlorine tablets (trichlor) are slow-dissolving and convenient, but they also contain cyanuric acid, which raises your CYA level over time. Liquid chlorine is unstabilized, does not raise CYA, and is ideal for fast sanitizing adjustments, though it must be added more frequently.