The most practical way to check the value of your inventory on Steam is to install a browser plugin called Steam Inventory Helper. It’s available for both Chrome and Opera, so you won’t need to install another browser on your computer.
Its main advantage is that it counts all items, regardless of how long ago you acquired them. This is important because recently, Valve introduced a new update where some items simply aren’t visible to third parties, including services, for up to 10 days. This is done for your security against scammers, but it also often causes a number of inconveniences.
Steam Inventory Helper can display the value of items based on both Steam and Buff163, which is convenient for traders. Moreover, it also allows you to view the float, pattern, and value of stickers.
This extension is completely safe, as you do not provide it with anything except the names of your skins.
Installing Steam Inventory Helper is very simple: just find it in the official store of your browser and click the install button. That’s it — now when using the web version of Steam, you will be able to see the value of your inventory.