I quit buying my local K-Mart brand of bleach as the labels did not indicate the % strength on them. I have my pool bleach requirements down to a science now and noticed I was unable to reach my maintenance level of chlorine using the quantities of bleach I was used to using. Thats when I searched the label, looking for the strength and there was none. Like others have said, if it isn't indicated, I assume it's 3% or less.