Breakpoint Dose
The breakpoint dose is the specific amount of free chlorine that must be added to destroy all combined chlorine in pool water.
In Plain Language
Breakpoint dose = 10 × (combined chlorine reading in ppm). If CC = 0.8 ppm, breakpoint dose = 8 ppm of additional FC. The current FC level must be added to the breakpoint dose to determine the total target FC: if current FC is 1.5 ppm and breakpoint dose is 8 ppm, target FC = 9.5 ppm. The shock calculator does not accept a combined-chlorine reading or compute this target itself -- select the closest available preset (5, 10, 15, or 20 ppm) for your product, or apply the shock dose formula directly for an exact figure.
Why It Matters
Calculating the exact breakpoint dose prevents under-dosing (which fails to destroy chloramines and wastes product) and over-dosing (which extends re-entry wait time).
Typical Values
Last reviewed: 2026-06-01