Steam Napkin Maths is a Chrome extension developed by Hugo "Coda" Kieffer. It falls under the category of Browsers and specifically the subcategory of Add-ons & Tools. This free extension provides estimations for the number of Owners, Wishlists, Gross Revenue, Net Revenue, and Average Playtime based on the data available on the Steam Store page.

Using Steam Napkin Maths is simple. When you are on the store page of a game, just click on the extension to bring up a popup that displays the estimated data. If you want more accurate results, you have the option to adjust the parameters to suit your preferences.

With Steam Napkin Maths, you can get a rough idea of the sales performance of a game on Steam without needing access to detailed sales data. It's a useful tool for both developers and gamers who want to gain insights into the popularity and success of games on the platform.