Open a CSV file and it looks like Excel with all the useful parts removed - no colors, no bold headers, no formulas, just plain text and commas. That's not a bug. CSV (comma-separated values) is deliberately minimal, and that's exactly why it's still everywhere decades after spreadsheets got good at everything else.
Why CSV still exists
Excel's native format (.xlsx) is actually a small zip archive full of XML files describing formatting, formulas, chart data, and more. That richness is great for humans working in a spreadsheet, but it's overkill for software that just wants your data - a database import tool, another company's system, a script you wrote, an old piece of software from 2004. All of those can read a CSV instantly, because a CSV is just rows of plain text. There's no formatting to parse, no formula engine required, nothing proprietary about it.
That's the core trade-off: Excel format is rich but Excel-specific. CSV is plain but universal.
When you actually need to convert
- Importing into another system. Databases, CRMs, email marketing tools, and accounting software very often want CSV specifically, even if you built the data in Excel.
- Working with code. If you or someone else is going to process the data with a script, CSV is far easier to read programmatically than a full .xlsx file.
- Keeping files small and diff-friendly. A CSV is plain text, so it's much smaller than the equivalent Excel file, and tools like git can actually show you what changed between versions - something that's meaningless for a binary .xlsx file.
- Sharing with someone on old or unusual software. Practically everything that opens spreadsheets at all can open a CSV.
What you lose in the conversion
Worth knowing upfront so nothing catches you by surprise:
- Formatting - colors, bold, column widths, all gone. CSV has no concept of any of it.
- Formulas - only the calculated result carries over, not the formula itself.
- Multiple sheets - CSV is a single flat table. If your Excel file has several tabs, you'll need to export each one separately.
If you need any of those preserved, keep working in .xlsx and only convert to CSV for the specific step that needs it.
Converting
- Excel (XLSX) to CSV
- CSV to Excel (XLSX), for the reverse direction
Both are instant - upload, convert, download, no formatting decisions to make along the way.