Quit rates are typically calculated by dividing the number of individuals who have successfully quit a behavior by the total number of individuals who attempted to quit, often expressed as a percentage. For example, if 100 people attempt to quit smoking and 25 succeed, the quit rate is 25%. This calculation can be adjusted based on different time frames, such as 3 months, 6 months, or 1 year, to assess the durability of the behavior change.