Your wishlist count (from Steamworks) against launches we measured: each one's Steam followers just before release and the copies our model credits it with by the end of its first full month.
You get the copies similar Steam launches sold in their first full month: a low, typical and high figure.
The calculators are free and need no account. A free account keeps your work: save launch plans, follow your own games on My games, and get alerts for the games you watch.