Steam does not publish how many people own a game, so nobody outside the studio knows the exact number. What you see is an outside estimate, shown as a range such as "1M–2M".
- Good for: a sense of scale. Is this game in the thousands or the millions? How do games like yours compare?
- Not good for: exact counts, or small changes from one week to the next.
- Only for released games, and not every game has one.
You find them on released game pages and in Comparable launches.
Estimated sales work differently. The Sales Estimator and the rival estimates on your Sales page start from reviews. With Steamworks connected, your rivals are estimated with your own sales per review, and the estimates get sharper as your game gathers reviews.
Tip: for your own game, skip the guessing. Connect Steamworks and see your real copies sold.