Keeping free chlorine in the right range keeps a pool safe and clear. This calculator estimates how much 12.5% liquid chlorine (sodium hypochlorite) to add to lift your pool from its current level to your target, based on volume.
Pool care
Keep it crystal.
Pool test kit
Measure FC accurately.
Liquid chlorine / shock
Dose to target.
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Frequently asked questions
What chlorine level should a pool be?
A free chlorine of 1–3 ppm is typical for residential pools; raise it after heavy use or rain.
Does this work for tablets?
This assumes 12.5% liquid chlorine. Tablets and granular shock have different strengths — check the label.