Excel to CSV Converter
A spreadsheet is a grid of values plus a large amount of everything else: formulas, formatting, multiple sheets, merged cells, charts. CSV is only the grid. Converting in either direction means deciding what to do about the difference, and this page is explicit about those decisions.
How to use it
- Choose XLSX to CSV or CSV to XLSX.
- Drop in the file. Parsing runs in the page, so financial data stays on your machine.
- Download the converted file.
Only the first sheet converts
CSV is a single table. A workbook with twelve monthly sheets has no CSV representation, so the first sheet is converted and the rest are not. This is a format limitation rather than a choice, but it catches people out because nothing visibly fails.
If you need all sheets, save each one separately from Excel first, or use the workbook itself as the interchange format. Where a downstream system genuinely requires CSV and your data spans sheets, the usual answer is to consolidate into one sheet with an extra column identifying the source, before converting.
Formulas become values
CSV has no concept of a formula. A cell containing =SUM(B2:B40) converts to the number that formula last evaluated to. The calculation logic is gone, and the value is frozen at whatever Excel had computed when the file was saved.
Two consequences follow. First, if the workbook was saved without recalculating, you export stale numbers. Second, a converted CSV is a snapshot, not a model, so re-importing it to Excel gives you a spreadsheet full of hard-coded constants that will not update when inputs change.
Cells showing an error state such as #REF! or #DIV/0! convert as that literal text, which will not parse as a number downstream. It is worth scanning for those before converting.
Dates and leading zeros, the two classic corruptions
Excel stores dates as a serial number counting days from an epoch, and displays them according to the cell format. When exporting, the display format decides what lands in the CSV, so the same underlying value can emerge as 03/04/2026 or 2026-04-03 or 45751 depending on how the cell happened to be formatted, and the first of those is ambiguous between two continents.
The counterpart problem is import. A CSV value like 3-4 is interpreted by Excel as a date and stored as 4 March, permanently. Part numbers, gene names, and version strings all suffer from this. Leading zeros go the same way: 00745 becomes 745.
The reliable defence in both directions is ISO 8601 dates written as YYYY-MM-DD, which no locale misreads, and importing genuinely textual columns as Text rather than General using the Excel import wizard rather than double-clicking the file.
What else does not survive
Cell formatting, colours, fonts, column widths, conditional formatting, data validation rules, merged cells, freeze panes, charts, pivot tables, and macros all have no CSV equivalent. Merged cells are worth flagging specifically, because the value lands in the first cell of the merged range and the rest become empty, which quietly shifts the shape of the data.
At a glance
| Accepted input | .xlsx, .csv |
|---|---|
| Sheets converted | First sheet only |
| Formulas | Exported as last computed value |
| Formatting | Not preserved |
Frequently asked questions
Why did only one sheet convert?
CSV represents a single table and cannot hold multiple sheets. Save each sheet separately from Excel if you need them all.
My part numbers lost their leading zeros. How do I stop that?
That happens on import into Excel, not during conversion. Use the Data then From Text import wizard and set the affected column to Text rather than General. Double-clicking a CSV skips the wizard and applies the damaging default.
Do my formulas carry across?
No. Formulas evaluate to values, and CSV stores the values. Converting back to XLSX gives you constants, not working formulas.
What date format should I use?
ISO 8601, written YYYY-MM-DD. It is unambiguous across locales, sorts correctly as text, and is understood by essentially every system that reads dates.
Read more
Working with documents: PDF, DOCX, and spreadsheets — Document formats encode intent as much as content, and conversions between them succeed or fail on whether that intent was recorded.