How much money I can earn with Unity Ads?

I’m ready to payment for google play developer account but I always think "Would I earn a lot money? ". How much money I can earn? How can I calculate money I would earn?

i know that unity ads pay ecpm(effective cost per mille) between 6-12 dollar.
so if you have 100,000 user that generate in your app/game 20,000 impression per month, you can earn between 120-240 dollar.