Most emulators (Citra, Panda3DS, Lime3DS) cannot run encrypted ROMs directly. Therefore, many users prefer a "decrypted" or "CCI" set. Additionally, "trimming" removes dummy data (empty padding used to fill cartridges). A trimmed ROM is smaller but functionally identical.
Let us cut to the chase. The exact size of a complete 3DS ROM collection depends on the following three variables. Here is the breakdown by set type as of 2025. 3ds Complete Rom Set Size
If you are setting up a personal 3DS archive, here is how to approach it: Most emulators (Citra
If you want updates, DLC, and VC titles included, you need 4TB . and VC titles included