Free tool
Chlorine & Shock Dosing Calculator
Liquid chlorine or cal-hypo — dial in the exact dose to hit your target free chlorine, or shock a green pool.
How to use this calculator
- 1Enter your pool volume
Don't know it? Use the Pool Volume Calculator first — this tool is built to work with that gallon figure.
- 2Choose raise or shock mode
"Raise free chlorine" moves FC from a current reading to a target. "Shock" computes a breakpoint dose from your combined chlorine reading.
- 3Pick your product and concentration
Select liquid chlorine or cal-hypo, then enter the exact % available chlorine from your product's label.
- 4Read your dose
The calculator shows exactly how much product to add, in gallons or pounds.
Frequently asked
Questions about chlorine dosing
Does this account for cyanuric acid (stabilizer)?
No — this calculator estimates the chlorine needed to raise free chlorine by a given amount, using standard liquid or cal-hypo dosing rules of thumb. It doesn't adjust for high cyanuric acid, which can make chlorine less effective ("chlorine lock"). If your CYA is above 80-100 ppm, you may need more chlorine than this estimate suggests.
What if I don't know my pool's exact volume?
Use the Pool Volume Calculator first to get a solid estimate, then come back here — the two tools are designed to work together.
What's the difference between shock mode and normal dosing?
Normal dosing raises free chlorine to a target level for everyday sanitizing. Shock mode uses breakpoint chlorination — roughly 10x your combined chlorine reading — to burn off chloramines and combined chlorine, the actual cause of that "chlorine smell" and eye irritation.
Why does the concentration field matter?
Liquid chlorine and cal-hypo products vary in strength — liquid is typically 10-12.5% available chlorine, and cal-hypo is typically 65-73%. A weaker product needs more volume to hit the same ppm rise, so always check your specific product's label and enter it here for the most accurate dose.