What Excel is
An Excel workbook is a zip archive of XML parts describing sheets, cells, formulas, styles and charts. The .xlsx extension is that format; .xls is the older binary one from before 2007.
Finance, operations and anyone who received a file from finance or operations.
What INI is
INI is the oldest configuration format still in daily use: named sections, then key equals value lines.
Windows software, PHP, Git and a long tail of tools that never moved on.
What changes when you convert Excel to INI
Only the first sheet is read, and cells are read as the text Excel displays rather than the number underneath. That matters for dates: a cell showing 15/03/2026 arrives as that string, not as a serial number you would then have to decode.
Each row becomes a section named after its first column, with one key per remaining column.
What carries over from Excel to INI
Excel records 5 things about a table that INI has no way to hold.
Excel distinguishes a number from the text of a number; INI does not, so every value arrives as text and has to be re-parsed by whatever reads it next.
An empty cell and a missing one are the same thing in INI, so a null and an empty string in the Excel both come out blank and can no longer be told apart.
A line break inside a cell ends the row in INI, so line breaks are replaced rather than carried through.
INI has no header row. The column names are repeated as keys on every record instead, which is why the result is bigger on disk than the table it came from.
Anything visual in the Excel - weight, alignment, colour, column widths - has no counterpart in INI and is dropped. The values are what survives.