Pool Chlorine Calculator
Free chlorine keeps pool water safe and clear. Enter your pool volume, current chlorine reading, and chlorine source — this calculator gives you the exact dose whether you use liquid chlorine, granular, or household bleach.
By Ellyana, creator of CalcClearly · Last updated
Your dosage will appear here
Enter your pool volume and readings, then click calculate.
Need to dial in shock, pH, or alkalinity too? See the full pool chemical calculator →
Quick Answer
Enter your pool volume, current chlorine reading, target level, and chemical source — the calculator gives you the exact ounces of liquid chlorine, granular dichlor, or household bleach to add.
How It Works: Formula & Variables
Dose = (Target − Current) × (Gallons / 10,000) × Chemical Factor
- Liquid chlorine (10–12.5%)
- Factor 12.8
- Granular dichlor (56%)
- Factor 2
- Household bleach (8.25%)
- Factor 15.5
- Household bleach (3%)
- Factor 42.7
Worked Examples
Example: Liquid chlorine
A 10,000-gallon pool reads 1 ppm free chlorine and needs to reach 3 ppm. Dose = (3 − 1) × (10,000 / 10,000) × 12.8 = 25.6 oz of liquid chlorine.
Key Concepts
Concentration matters: A given volume of bleach has far less active chlorine than the same volume of pool-grade liquid chlorine — always check the label percentage.
Indoor vs. outdoor targets: Indoor pools need higher free chlorine (3–5 ppm) since there's no sunlight to help break down contaminants.
Common Mistakes
Using scented bleach: Only use plain, unscented household bleach — fragrances and additives can cloud water or irritate skin.
Letting chlorine bottom out: Once free chlorine hits 0 ppm, algae and bacteria can take hold quickly — top up before it runs out.
Frequently Asked Questions
For a 10,000-gallon pool, expect to add 10–13 oz of liquid chlorine (10%) per week to maintain 3 ppm. Hot weather, heavy use, and UV exposure increase demand.
Yes, but use unscented bleach only and account for concentration — standard bleach is 3% or 8.25%, while pool-grade liquid chlorine is 10–12.5%. This calculator adjusts the dose for each type.
1–3 ppm for outdoor pools. 3–5 ppm for indoor pools or pools with high bather load. Never let free chlorine drop below 1 ppm.
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