"Possible data loss" when saving as CSV
Excel warns, and it is right: a CSV only keeps the values of the active sheet. But what gets lost is not always what you expect.
What the message says
A CSV is a text file: one line per row, values separated. Everything that is not a visible value of the active sheet disappears.
Why it appears
- The other sheets: only the active sheet is saved.
- Formulas: only their result is written.
- Formatting, charts, comments.
- Less expected: leading zeros and long numbers, read back as numbers when reopened; accents, depending on the encoding chosen.
Making it go away
- Choose "CSV UTF-8" rather than plain "CSV (Comma delimited)" if the file goes to modern software.
- Save each sheet separately if several must go.
- Keep the original workbook: the CSV is an output copy, not a working format.
The tool that handles it
Convert a spreadsheet produces one CSV per sheet in one go, in the encoding and separator you want, leading zeros and long numbers included. For an already damaged CSV, Fix a CSV.
Frequently asked questions
- Why do my accents become "é"?
- The CSV was saved in one encoding and read in another. Fix a CSV recognises the mix-up and fixes every accent.