Starfield has two PC storage models that should never be collapsed into one instruction. Standard PC/Steam saves are recognizable .sfs files, while the Microsoft Store/Xbox app build uses the Windows Gaming Services container. That distinction matters for backup, migration, and any future SaveEditor tool. If you use Steam, preserve the complete Starfield Saves directory and, when relevant, its Steam remote copy. If you use the Xbox app, preserve the WGS data first and do not rename opaque WGS files into .sfs files.
Known Starfield save-file structure
The researched filename or folder pattern is *.sfs. File-extension context: .sfs The documented format notes are: The standard PC save files use the .sfs extension. Microsoft Store/Xbox app saves use the Windows Gaming Services (WGS) container instead of the same visible-file layout as the standard Documents save folder.
Why an extension is not enough
A save filename can identify a likely container, but it does not prove the internal schema, game version, checksum rules, encryption state, or editability. A visible .sfs file from the standard PC layout is not the same thing as a Microsoft Store WGS container. Storefront conversion requires a purpose-built workflow rather than extension changes. SaveEditor therefore separates file identification from Tool compatibility and only labels a game-specific Tool Verified when its exact profile/version evidence passes the runtime gate.
Where the format is stored
PC save locations: Windows: Standard Windows: %USERPROFILE%DocumentsMy GamesStarfieldSaves
Steam remote copy: <Steam-folder>userdata<user-id>1716740remote
Microsoft Store: %LOCALAPPDATA%PackagesBethesdaSoftworks.ProjectGold_3275kfvn8vcwcSystemAppDatawgs<user-id> | Linux / Steam Play: Steam Play: <SteamLibrary-folder>/steamapps/compatdata/1716740/pfx/; Steam Cloud may also use the matching userdata/1716740 area.. Storefront context: Steam, Microsoft Store / Xbox app. Steam and Microsoft Store use materially different storage layouts. Treat WGS data as a separate container workflow instead of renaming files between storefronts. This matters because two releases can use different containers or companion files even when the visible slot name is similar.
Back up before inspecting or editing
For Steam/standard Windows, copy the full Saves folder. For Microsoft Store, back up the WGS container before attempting any extraction or storefront migration. A read-only viewer is lower risk than a writer, but the live save should still be copied first. Cloud context also matters: Steam Cloud and Xbox Cloud are documented. The Documents folder may also be synchronized by OneDrive when Windows folder backup is enabled. Keep the original bytes available so any experiment can be reversed without relying on a cloud service or automatic backup.
What this reference does not claim
This page does not infer an undocumented checksum algorithm, encryption key, compression layer, or cross-store conversion from the file extension. Troubleshooting evidence: If expected saves are not in Documents, identify the storefront first. OneDrive folder redirection and WGS storage are common reasons the obvious path does not match the active copy. Those questions require a verified parser/profile or a game-specific source, not a generic format guess.
Verification context: Windows, Steam, Microsoft Store, Steam Play, and cloud locations were reviewed against current PCGamingWiki coverage for Starfield.