The number of customers each Customer Success Manager (CSM) should handle at $20,000 ACV is ideally between 50 and 100.
A good benchmark is for each CSM to manage $1M to $2M in ARR, depending on the growth stage and resources of the company.
Early on, it is recommended to target $1M in ARR per CSM for high-touch engagement and retention, whereas as you scale, you can aim for $2M per CSM.
The ratio of customers per CSM may vary based on whether the company focuses on SMB, mid-market, or enterprise clients, with enterprise clients typically requiring more hands-on support.