A dispute rate can be calculated by taking the number of disputes received for a given time frame and dividing that number by the total number of sales transactions processed in that given time.
It helps to analyze your dispute rate month-to-month, so you should set your time frame to 30 days. E.g., Within the last 30 days, calculate the total sum of disputes you received, and then divide that number by the total sum of processed transactions. Your formula will be formatted like this:
[Dispute Volume / Transaction Volume] = DR
If you prefer, multiply your result by 100 in order to view it as a percentage.