How do you calculate client retention rate?

What is your customer retention rate? Number of current customers __5086___. Total number of customers served in the past 12 months:__256___. Customer Retention Rate = #1 ÷ #2 = _____ (your percentage of retention). What is your goal for your customer retention rate this year? _____ *It is important to measure the change in this number with regularity. *When it is below 80%, then it is a serious area of concern.