What Does Formatting Mean on a PSP?

“Formatting” on PSP has two completely different meanings depending on context.

1. Formatting the Memory Stick (Most Common)

Wipes **all data** on the Memory Stick Duo/Pro Duo and restores a clean FAT32 filesystem.

• Why do it? Prep a new stick, fix corruption, erase personal data before selling.
• How: Settings → System Settings → Format Memory Stick → Confirm. **Back up saves/ISOs first!**
• On PC: Right-click drive → Format → FAT32, 32 KB allocation unit.

2. Formatting a Game File (ISO/CSO Conversion)

Converting a game dump to a PSP-playable container.

• ISO → CSO: Compresses ~30–60% smaller (good for 4–8 GB sticks). Use UMDGen, PSP ISO Compressor, CisoPlus.
• CSO → ISO: Decompress for faster load times / compatibility with picky homebrew.
• Folder (JB) → ISO/CSO: Some homebrew dumps as loose files; pack into ISO for CFW launchers.

Key Reminders

• **Formatting the stick = data loss.** Backup first.
• **Formatting a game = file conversion only.** Content unchanged.
• Tools: UMDGen (Windows), psp-tools (cross-platform).

Context decides which one you need.