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Pool Chlorine Calculator

Reviewed 2026-04

CYA (cyanuric acid, the chlorine stabilizer) -aware dosing for liquid chlorine, bleach, dichlor, or cal-hypo. Enter your pool size, current FC (free chlorine), and CYA level. Get a dose estimate for the stated strength.

Built on CDC and ANSI pool-water standards

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Know your exact size? Use the Volume Calculator →

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Unknown CYA must stay unknown. Get a fresh CYA reading before choosing an FC target; use a suitable test or pool-store test. One option is a 4-in-1 test kit (Amazon →) or want to dose stabilizer? Use our CYA dosing calculator →

Chlorine source
Confirm your inputs

Examples remain unconfirmed until you check each value. Confirm fresh test results and your measured pool volume before using a dose. Editing a value clears its confirmation.

Popular liquid chlorine

Enter your pool data above for personalized quantities

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Top Pick

Champion

Liquid Chlorine (1-Pack) · 1 gallon jug (12.5%)

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ProSide

Chlorinating Liquid (10%) · 2-gallon case (10%)

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Unstabilized chlorine equilibrium only

This approximate table applies only without CYA. With stabilizer, these percentages do not describe the active fraction of measured FC; use measured CYA to choose chlorine targets.

pHActive HOCl %Note
7.073%High effectiveness
7.266%Good
7.455%Optimal: target range
7.644%Acceptable
7.833%Getting low
8.025%~25%, NOT <3% (common error)
9.03%<3%, this is where the "3%" figure applies

Source: ANSI/PHTA/ICC-11 §5.3 chlorine-species pH equilibrium tables (canonical source IDs CS-013 and CS-014). At pH 8.0: only ~25% HOCl (not <3%; that only applies at pH 9.0+).

Frequently asked questions

How do chlorine targets depend on CYA?

Use measured CYA. Routine FC must meet at least the CDC floor of 1 ppm without stabilizer or 2 ppm with stabilizer, and the higher CYA-dependent minimum where applicable. This tool does not substitute a made-up CYA value when it is unknown. Its routine calculator withholds additions for FC above 10 or targets above 10; use the separate algae-treatment workflow when appropriate.

Does a calculated dose mean the water is safe to swim in?

No. Confirm adequate FC for measured CYA, valid pH in the 7.2–7.8 routine range, clear water, no visible algae and all product re-entry instructions. Test FC and pH at least twice daily and more often during heavy use or treatment. No single upper FC threshold is swimming clearance.

Which chlorine strength should I select?

Use the actual label and concentration basis. Pool liquid presets use trade-percent available chlorine per volume. Household bleach presets use weight-percent sodium hypochlorite converted using approximate density and chlorine equivalence. Dry products use available chlorine, which differs from ingredient purity. Only products matching the selected chemical, normalized strength and basis are shown.

How should I add chlorine?

Follow the exact product and surface instructions. Liquid and granular application methods differ. Some granular labels require pre-dissolving and others prohibit it. Never mix chemicals. After the instructed circulation/wait period, measure again and recalculate any further addition.

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How we calculate this
Our formulas follow ANSI pool-water standards and are validated against CDC pool-water health code guidelines. We show you the math so you can verify every result. Questions or corrections? Please contact us.