Recently we had a discussion of grocery store bleach vs chlorinating liquid and the relative merits of each in view of concentration and degradation.
I buy chlorinating liquid from the pool store in 5 gallon carboys for $14.75 plus tax. It is said to be 12.5% and I don't doubt that's true at the moment of manufacture but I'm sure it has degraded to some extent by the time I use it. When I input the different variables in the Pool Calculator I've commonly used 10% as my chlorinating liquid concentration.
Today I decided to do the actual testing using a 5 ml pipette and a 50 ml graduated cylinder. I made a dilution of 1 ml : 100 ml, mixed it well, and made a second 1:100 dilution. Then I tested two samples, a 25 ml using the 0.2 multiplication factor and a 10 ml using the 0.5 factor.
My results were 9.4 ppm in the first and 11 ppm in the second sample. That's close enough to 10% for kitchen counter chemistry.