The overlap size
The number of users that follow all profiles on the list.
If you want to estimate the audience overlap for 5 accounts, there’s a good chance the overlap size will be quite small.
This is due to the fact that if there is a single influencer with a unique audience, it’s likely it won’t overlap with other influencers’ audiences. For example, if your list includes 1 Australian blogger and 4 influencers from Russia, there will be very little overlap between the former and the latter.
We recommend that you check the Top Options or Overlap Matrix sections. They’ll illustrate similar cases.