PCSX2 save files are generally located in a memcards folder within the Documents directory for Windows installers, or directly inside the program folder for portable versions [1]. Linux users typically find saves in ~/.config/pcsx2/memcards, while macOS users should check ~/Library/Application Support/PCSX2/memcards [1].
Conclusion
:\PCSX2\memcards and sstates folders inside the main installation directory.This mimics a physical PS2 memory card (8MB or larger virtual file). When you save "normally" inside a game (e.g., using a Save Point in Resident Evil 4 or an Inn in Dragon Quest VIII), the data is written to a virtual memory card file with the extension .ps2 or .bin.
By default, 8MB (exactly like a Sony MagicGate card). However, you can use the Memory Card Manager to create 16MB, 32MB, or even 64MB cards. Warning: Some games (notably Star Wars Battlefront II and Rogue Galaxy) do not recognize larger than 8MB and will corrupt saves.