Hello @stanleypop,
Great question!
As you are aware, Klaviyo’s List Growth Reporting would only provider a report for individual lists. At present there isn’t a method to report on the growth of a culmination of all your available lists in your Klaviyo account. I am aware that this is a highlight sought after feature and will share your feedback and use case to your Product Team to explore!
Another potential option would be to use the Subscribe to List metric to gauge your list growth. Because the List Growth metric would track all contacts who have subscribed and added to a list, building reports or reviewing this metric under your analytics tab would be a great alternative to an account wide list growth report. One thing to keep in mind when using this metric however, is that this metric will not be recorded in a number of small circumstances such as if contacts were being added to a Klaviyo list via the depreciated list V1 endpoint, if contacts were added to the list via a .CSV upload without email consent, or if they were added via the copy/paste method. This is further explained in the Understanding the Subscribed to List Metric Help Center article.
In addition I know @nikitavaidya and @julie.accardo also had alternative solutions to gather list growth for various list in their comments in the following Community post:
I hope this helps!
David