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 DAX is
A DAX DATATABLE expression that defines a table inline in a Power BI model.
Power BI report authors.
What changes when you convert Excel to DAX
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.
All columns are declared as STRING. Change the type declarations by hand if you need numeric columns.
What carries over from Excel to DAX
Excel records 3 things about a table that DAX has no way to hold.
An empty cell and a missing one are the same thing in DAX, 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 DAX, so line breaks are replaced rather than carried through.
DAX marks its header cells differently from its data cells, so the first row is written with that marker.
Anything visual in the Excel - weight, alignment, colour, column widths - has no counterpart in DAX and is dropped. The values are what survives.
Both formats record types, so numbers, booleans and nulls survive as themselves rather than as text.