Almost every system that imports data wants a CSV — accounting packages, CRMs, mailing platforms, databases, statistical software. Upload your .xlsx or .xls above and get a plain, universally readable data file back.
The conversion is simple. What is not simple is what CSV quietly throws away, and the handful of things that silently corrupt data on the way in and out. Both are below.
A CSV is a text file of values separated by commas. That is the entire specification. It is the format's strength — anything can read it — and the reason so much is lost in translation.
What survives: the cell values themselves, exactly as displayed.
What does not:
If any of that matters, Excel to PDF preserves the appearance and Excel to HTML keeps the table structure for a web page.
"CSV" means comma-separated values, and a great many CSV files are not separated by commas.
In much of Europe and South America the comma is the decimal separator — 1.234,56 rather than 1,234.56 — so using it between fields as well would be ambiguous. Those systems use a semicolon instead, and Excel switches automatically based on your regional settings.
This is why a file exported on a French or German computer often will not open correctly on an English one. The symptom is unmistakable: every row lands in a single column with the semicolons visible as ordinary characters.
If the destination system expects one or the other, check before you send. Opening the finished CSV in a plain text editor takes five seconds and shows you exactly what separates the values.
These are the failures that produce no error message, which is what makes them dangerous.
Leading zeros disappear when reopened. The CSV itself stores 02134 correctly. But open that file by double-clicking it, and Excel reads the column as numeric — postcodes, French phone numbers starting 06, account references like 000451 all lose their zeros. The file was fine; the reopening broke it.
Long numbers become scientific notation. A sixteen-digit card reference or a product barcode reappears as 1.23457E+15, and Excel rounds anything beyond fifteen significant digits. That value is genuinely lost.
Text that resembles a date becomes one. Part codes, gene names, a ratio written 1/4. Well documented enough in genomics that researchers renamed identifiers to work around it.
The fix: do not double-click a CSV to open it. In Excel use Data → From Text/CSV, which lets you set each column's type before import — mark the affected ones as Text and everything survives intact.
Two smaller issues that produce confusing results.
Fields containing the delimiter must be quoted. A company name like Smith, Jones & Co in a comma-separated file has to be written "Smith, Jones & Co", or it reads as two fields and every column after it shifts by one. Proper exporters handle this automatically; hand-built files often do not. If one row has more columns than the rest, an unquoted comma is almost always why.
Encoding decides whether accents survive. A CSV carries no record of its own character encoding, so software has to guess — and a wrong guess turns Müller into Müller. UTF-8 covers every language and is what modern systems expect. Worth noting that Excel's own plain "CSV" export uses a legacy encoding on many systems; choose CSV UTF-8 where it is offered.
A clean CSV starts with a clean worksheet. Three things worth two minutes.
One header row, immediately above the data. Title rows, merged banner cells and blank spacer rows all become data rows in the output, and most import tools expect the first line to be the field names.
Check the used range. Press Ctrl + End. If the cursor jumps somewhere far below or right of your data, the sheet carries formatting on empty cells — and those become rows of empty commas in your CSV. Delete the surplus rows and columns, then save and reopen.
Resolve error values. Cells showing #REF!, #N/A or #DIV/0! export as that literal text and will break most imports. Find them before converting, not after.
CSV to PDF turns raw data into a readable table, Excel to PDF keeps the formatting, Excel to HTML prepares a table for a web page, and PDF to Excel works the other way. Browse all Excel tools.