For most creators, the number of people who become supporters on FANBOX is about 1% of their followers on Twitter, pixiv, YouTube, and other social media.
For example, if you have 1000 followers on Twitter, about 10 of them might support you on FANBOX.
However, this is an average figure based on aggregated data. Depending on the creator, the number might be less than 1%, or higher than 3%. However, please use these data as a guideline.
Everyone who joins FANBOX starts with zero supporters, so you can't expect 1% of your followers on social media to support you right away.However, if you are serious about promoting yourself and making announcements, you will likely get to the 1% mark more quickly.