The percentage of customers that place a 2nd order.
Formula
New Customer Repurchase Rate = Repeat Customers / Customers
Explanation
The percentage of your customers have placed more than one order. Sometimes this is also just called Repurchase Rate.
Notes
Sometimes, this metric will be displayed in conjunction with a time period - eg. New Customer Repurchase Rate 90 days
If this is the case, the displayed value shows you what percentage of customers that have placed a second order within 90 days of their first order.