To calculate the CPA from the CPL, you need to take into account the conversion rate of leads into customers and the average revenue generated per customer. First, calculate the conversion rate by dividing the number of customers obtained from the leads by the total number of leads. Next, determine the average revenue per customer by dividing the total revenue generated by the number of customers. Finally, multiply the CPL by the conversion rate and divide by the average revenue per customer to obtain the CPA. The CPA formula = (CPL x Conversion rate) / Average revenue per customer = CPA.