Pool Chlorine Calculator

Q: How much chlorine to shock a pool?

Routine shocks target 10 ppm; algae and cloudy water need 20-30 ppm depending on stabilizer. The shock tab calculates the amount from your volume and current level.

Q: Daily chlorine or shock - which do I need?

Daily maintenance keeps 1-3 ppm steady; shock is a one-off treatment after storms, parties, algae or high combined chlorine.

Q: Which chlorine product is best?

Liquid 12.5% adds no stabilizer or calcium. Tablets add CYA, cal-hypo adds calcium, dichlor adds CYA. The calculator notes each side effect with your dose.

Q: Can I dose in litres instead of gallons?

Yes - convert litres by dividing by 3.78541 to get gallons, and switch the dose display to metric (g / mL / kg) with the units selector.

Calculate daily chlorine needs and shock treatment doses — in gallons or litres

Shock Treatment Calculator

Chlorine Types

Tablets (Trichlor)

Slow-release, convenient. Contains stabilizer. Use in floaters or feeders.

Granular (Cal-Hypo)

Fast-acting, great for shocking. Adds calcium to water.

Liquid Chlorine

Quick results, no residue. Loses strength over time.

What to look for when buying chlorine

Check the active strength. Liquid chlorine is typically 10–12.5% sodium hypochlorite; granular products vary. The label dose is based on that strength, so a weaker bottle needs more volume for the same ppm rise.
Match the product to its side effect. Trichlor and dichlor add stabilizer (CYA), cal-hypo adds calcium, and liquid chlorine adds neither. If your CYA or calcium is already high, choose accordingly.
Read the ingredients and date. Avoid products with undisclosed fillers or clumping. Liquid chlorine loses strength over time, so fresher stock is better.
Store it safely. Keep containers sealed, upright, cool, and dry, away from other chemicals and sunlight. Never mix chlorine products.
Use a reliable test kit. Dosing without a current free-chlorine and CYA reading is guesswork. A FAS-DPD kit is more precise than color-match strips for shock levels.

When to Shock

• Weekly during peak season
• After heavy rain or storms
• When water is cloudy
• After pool parties or heavy use
• When you see algae starting
• When chlorine smell is strong (chloramines)

Safety Tips

• Shock in evening to avoid sun degradation
• Run pump for 8+ hours after shocking
• Don't swim until chlorine drops below 4 ppm
• Never mix different chlorine types
• Store in cool, dry place away from moisture

Next step

Chlorine dosing works, but the water must stay balanced for it to be effective.

Fix pH & TA →Chemical spend →

Pool chlorine calculator FAQs

How much chlorine do I add per gallon?

About 1 fl oz of 12.5% liquid chlorine raises 10,000 gallons by roughly 1 ppm. Enter your pool volume in gallons (or litres), your current and target levels, and this pool calculator gallons tool returns the exact dose in oz, fl oz, lbs, g or mL.

How much chlorine to shock a pool?

Routine maintenance shocks to 10 ppm; algae and cloudy water need 20–30 ppm depending on stabilizer. Select your reason in the shock tab and the calculator works out the amount from your volume and current level.

Daily chlorine or shock — which do I need?

Daily maintenance keeps 1–3 ppm steady; shock is a one-off slam that oxidates contaminants and raises chlorine fast (after storms, parties, algae or high combined chlorine).

Which chlorine product is best?

Liquid 12.5% adds no stabilizer or calcium — the pro pick. Tablets are convenient but add CYA (~0.6 ppm per 1 ppm FC); cal-hypo adds calcium; dichlor adds CYA. The calculator notes each side effect with your dose.

Can I dose in litres instead of gallons?

Yes — enter volume in gallons (the shared pool calculator gallons input) or convert with litres ÷ 3.78541, and switch the dose display to metric (g / mL / kg) with the units selector.