Net New ARR is how much total ARR a company adds in a period, net of churn.
Net New ARR for month x = ARR in month x - ARR in month (x-1)
The trajectory of Net New ARR is a good leading indicator of a company’s future growth rate. If Net New ARR is increasing each period a high CMGR can be sustained, but if Net New ARR is flat month over month, CMGR will decline over time.