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 PNG is
A lossless image format. Text and thin lines stay exactly as drawn, which is what a table is made of.
Slides, chat messages, issue trackers, and anywhere a table has to travel as a picture rather than as data.
What changes when you convert Excel to PNG
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.
The table is drawn from the data onto a canvas rather than captured from the page, so the whole thing comes out however long it is and however much of it is on screen. Column widths are measured from the content, alternating rows are shaded, and the scale is adjustable so a table for a slide or a print layout can be drawn at two or three times the size.
What carries over from Excel to PNG
Excel records 4 things about a table that PNG has no way to hold.
Excel knows which of its values are numbers. PNG keeps only their appearance, so nothing downstream can sort or sum them without someone reading them back off the image first.
An empty cell and a missing one are the same thing in PNG, so a null and an empty string in the Excel both come out blank and can no longer be told apart.
Nothing in PNG records that the first row is a header. It is drawn at the top and looks like one, which is all that is left of the distinction.
PNG is the end of the line for this data. Reading the table back out of it is a separate and much harder problem than writing it, so keep the Excel if you will need the values again.