Example:
Free space for the file in the below query result set will be returned by the FreeSpaceMB column.
SELECT DB_NAME() AS DbName,
name AS FileName,
type_desc,
size/128.0 AS CurrentSizeMB,
size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS INT)/128.0 AS FreeSpaceMB FROM sys.database_files WHERE type IN (0,1); Reference:
https://www.sqlshack.com/how-to-determine-free-space-and-file-size-for-sql-server-databases/