Pool Chlorine & Chemical Calculator
Work out how much chlorine (liquid, cal-hypo or trichlor) raises free chlorine by a target amount, and how much shock you need for your pool's volume.
How to use
- 1Enter the pool volume in gallons and the current and target free chlorine (ppm).
- 2Choose the chlorine product you're using.
How it's calculated
Per 10,000 gal, to raise free chlorine by 1 ppm: 12.5% liquid chlorine ≈ 10.7 fl oz; 10% ≈ 13 fl oz; 73% cal-hypo ≈ 1.8 oz (by weight); 65% cal-hypo ≈ 2 oz; 90% trichlor ≈ 1.5 oz. Dose scales with gallons and ppm change.
Frequently asked questions
What free chlorine level should a pool have?
About 1–3 ppm for most residential pools (CDC recommends at least 1 ppm), higher with stabilizer (CYA) — a common guide is FC ≈ 7.5% of CYA.
How much should I shock?
Shocking usually means raising FC to about 10 ppm (or 40% of CYA for algae) — use the target field.
Is it safe to add chemicals directly?
Follow the product label. Never mix different chlorine products together, and add chemicals to water, not water to chemicals.