Convert CSV to Excel (XLSX)
Free online converter for CSV files. Office Open XML workbook. Nothing to install, no watermark, and every file is deleted automatically.
Drag and drop your files
or
Upload a CSV file to convert it to Excel (XLSX). Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About CSV and XLSX
CSV .csv
Rows of plain text with values separated by commas. No formatting, no formulas, no sheets — just the data, which is what makes it universal.
Good for
- Readable by every spreadsheet, database and programming language
- Tiny, and trivial to generate or parse
- Nothing hidden — the file is exactly what it appears to be
Trade-offs
- One table only: no sheets, formulas, colours or charts
- No standard for encoding, so accents and symbols often corrupt
- Commas and line breaks inside values need careful quoting
text/csv
Excel (XLSX) .xlsx
Excel's modern workbook format — zipped XML holding sheets, formulas, formatting and charts.
Good for
- Keeps live formulas, not just their results
- Multiple sheets, charts and conditional formatting
- The default in nearly every business
Trade-offs
- Formula compatibility varies between spreadsheet applications
- Heavier than CSV for plain tabular data
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
CSV and XLSX side by side
| CSV | XLSX | |
|---|---|---|
| Compression | None — plain text | Zipped XML |
| Animation | No | No |
| Typically used for | Data exchange, imports and exports, reporting | Spreadsheets, financial models, reports |
What changes when you convert CSV to XLSX
Your text acquires types
A CSV is text: every field is a string, and nothing in the file says otherwise. A spreadsheet has real types, so opening one means guessing which columns are numbers and which are dates. That guess is where data gets damaged — a product code of 00123 can arrive as the number 123, a long identifier can be rewritten in scientific notation, and 03/04 is a date whose meaning depends on where the reader thinks it is from. Check any column of codes, identifiers or part numbers before you rely on the result.
It becomes a real workbook
The output is a genuine XLSX rather than a CSV with a new extension: the first row is treated as a header, set in bold and frozen so it stays visible while scrolling, and column widths are set from the header text. From there it behaves like any other workbook — formulas, additional sheets and formatting all become available.
Read directly, never opened
No spreadsheet application is involved in this conversion. The file is parsed in our own process and the data is written straight out, which is both faster than launching an office suite and safer: macros in a workbook are never in a position to run, because nothing here is capable of running them. It also means the output is exactly the data, with none of an office suite's opinions about formatting applied on the way through.
There is a ceiling on rows
A spreadsheet is not a database: the format tops out at 1,048,576 rows and 16,384 columns, and a file approaching either becomes painful to open long before it reaches them. CSV and JSON have no such limit. If your data runs to millions of rows, converting it into a workbook is usually the wrong move — keep it as text and query it with something built for the volume.
Read as UTF-8
A CSV is a text file, and a text file does not record which encoding it uses — that is the one thing the format cannot tell you about itself. We read it as UTF-8, which is right for essentially anything produced this decade. A file saved long ago in a regional encoding can arrive with accented characters mangled, and the fix is to re-save it as UTF-8 before converting rather than after. Tabs and spaces used to line columns up will also shift once the text is set in a proportional typeface.