This calculator is designed to receive MTG cards for a combo and it is going to calculate how many token it creates and how much damage does it do.
While you could technically use existing software like Magic Arena or Magic Online for these calculations both have the disadvantage that they have to calculate many more things on each card: its cost, owner, order in which they entered (it is needed for layer desicions). This causes them to have a relative low limit on how much does them calculate before they stop trying. This calculator will try to only calculate necesary information for combos so you can know how much damage does them really do.