One of the most important factors in any business is how you keep your customers. This includes everything from customer service and retention through marketing efforts to training for new hires, professional services like CRM systems implementation or website maintenance- it all adds up! Customer Retention Cost is the total cost of retaining a customer. This includes all costs associated with their success, service and engagement to ensure they continue coming back for more! The formula is: Customer Retention Cost = Total Customer Retention Cost / Number of active customers