Windows Registry Limits

Registry Element Size Limit
Key name 255 characters. The key name includes the absolute path of the key in the registry, always starting at a base key, for example, HKEY_LOCAL_MACHINE.
Value name 16,383 characters

Windows 2000:  260 ANSI characters or 16,383 Unicode characters.

Value Available memory (latest format)

1 MB (standard format)

Tree A registry tree can be 512 levels deep. You can create up to 32 levels at a time through a single registry API call.

Long values (more than 2,048 bytes) should be stored in a file, and the location of the file should be stored in the registry. This helps the registry perform efficiently.

The file location can be the name of a value or the data of a value. Each backslash in the location string must be preceded by another backslash as an escape character. For example, specify “C:\mydir\myfile” to store the string “C:mydirmyfile”. A file location can also be the name of a key if it is within the 255-character limit for key names and does not contain backslashes, which are not allowed in key names.