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Pool Chlorine Calculator
How much liquid chlorine, bleach or cal-hypo raises free chlorine to your target.
How it's calculated
Parts per million is milligrams of chlorine per liter. Liquid chlorine strength is the percent of available chlorine by weight-per-volume, so gallons needed = ppm increase × pool gallons ÷ (strength % × 10,000). Granular products: pounds = ppm × gallons × 8.34 ÷ 1,000,000 ÷ the product's available-chlorine fraction (0.65 for cal-hypo, 0.56 for dichlor).
Example
Raising a 15,000-gallon pool from 1 to 4 ppm with 10% liquid chlorine: 3 × 15,000 ÷ 100,000 = 0.45 gal — about 58 fl oz.
Free chlorine targets (with cyanuric acid)
| CYA (stabilizer) | Minimum FC | Target FC |
|---|---|---|
| 0 ppm | 1 | 1–3 |
| 30 ppm | 2 | 3–5 |
| 50 ppm | 4 | 5–7 |
| 70 ppm (salt pools often run here) | 5 | 6–8 |