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 Markdown is
A Markdown table is rows of pipe-separated cells with a dashed rule under the header. Alignment is set by placing colons in that rule.
README files, GitHub issues, documentation sites, Obsidian and Notion.
What changes when you convert Excel to Markdown
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.
Cells are padded so the source lines up in a plain text editor, pipes inside values are escaped, and line breaks inside a cell become <br> because a Markdown table row cannot span lines.
What carries over from Excel to Markdown
Excel records 4 things about a table that Markdown has no way to hold.
Excel distinguishes a number from the text of a number; Markdown 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 Markdown, 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 Markdown, so line breaks are replaced rather than carried through.
Markdown 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 Markdown and is dropped. The values are what survives.