How Much Shock Does Your Pool Need?
"Shocking" just means adding a big dose of chlorine to blast past breakpoint — clearing out chloramines, bacteria, and algae in one go. The amount depends on three things: your pool's volume, how far you need to raise free chlorine, and which product you're using.
The calculator above handles all three. Pick your shock type from the dropdown and it converts the dose into pounds, ounces, or gallons automatically. If you don't know your volume yet, run the Pool Volume Calculator first.
Pool Shock Chart (Cal-Hypo, to ~12 ppm)
Rough amounts of 73% cal-hypo shock to take a pool from ~1 ppm up to a 12 ppm shock level:
| Pool Size (gallons) | Cal-Hypo (73%) | 1 lb Bags |
|---|---|---|
| 5,000 | ~0.6 lbs | ~1 |
| 10,000 | ~1.3 lbs | ~1.5 |
| 15,000 | ~1.9 lbs | ~2 |
| 20,000 | ~2.5 lbs | ~2.5 |
| 25,000 | ~3.1 lbs | ~3 |
For a green, algae-filled pool you'll need to shock harder and repeat — see our guide on clearing a green pool.
When to Shock Your Pool
- Weekly to biweekly as routine maintenance during swim season
- After heavy use (a pool party or lots of swimmers)
- After heavy rain or a storm
- When the water looks cloudy or green, or smells strongly of chlorine (that smell is chloramines, not "too much chlorine")
- After opening or before closing for the season
Test your free and combined chlorine with a good test kit before and after so you know the shock actually worked.