What is a CSV file?
CSV stands for Comma-separated values. It was created by no single author; standardised in RFC 4180 and first released in 1972. A CSV file holds a single table as plain text, with commas between values. It has no formatting, formulas or multiple sheets, which is exactly why every program can read it.
| Type | spreadsheet |
|---|---|
| Compression | Lossless |
| In a browser | opens in every spreadsheet program and any text editor |
| Common uses | data exports, imports into databases and exchanging tables between programs |
| MIME type | text/csv |
Which format should you convert CSV to?
- CSV to XLSX to open in Excel with every sheet and formula.
- CSV to ODS for LibreOffice and open-standard requirements.
- CSV to XLS for older software that only reads Excel 97 to 2003 files.
How to open a CSV file
Whether a CSV file opens with a double click depends on the device. Here is what works on each, without buying software:
| Windows | Excel opens it on Windows; Google Sheets and LibreOffice Calc are free alternatives. |
|---|---|
| Mac | Numbers opens it, as do Excel for Mac and LibreOffice Calc. |
| iPhone and iPad | Numbers, Google Sheets and the Excel app open it from the Files app. |
| Android | Google Sheets and the Excel app open it from Files by Google. |
| Web browser | CSV opens in every spreadsheet program and any text editor. |
Want the technical details? See what a .csv file is, with its MIME type, file signature and a viewer.
CSV compared with other spreadsheet formats
How CSV stacks up against the formats people most often convert it to or from:
| Format | Compression | Usually contains | Released | Best for |
|---|---|---|---|---|
| CSV | Lossless | one table of plain text values, one row per line | 1972 | data exports, imports into databases and exchanging tables between programs |
| XLSX | Lossless | several sheets with values, formulas, formatting and charts | 2007 | business spreadsheets, reports and anything shared with Excel users |
| XLS | Lossless | several sheets with values, formulas and formatting in a binary file | 1997 | older Excel files and systems that still export the legacy format |
| ODS | Lossless | several sheets with values, formulas and formatting | 2005 | LibreOffice and OpenOffice users and public-sector documents |
How to use the CSV converter
- Choose the format you want in the Convert to menu.
- Drop your CSV files on the box, or press Choose CSV files. Several files can go in at once.
- Adjust the settings if you need to; the defaults suit most people.
- Press Convert and save each file with its Download button. Converting to HTML, JPG, PDF, PNG uses our server, which deletes the file right after; the rest never leave your device.
Tips for converting CSV files without losing anything
Converting a CSV file keeps every value exactly; what can change is structure, such as extra sheets, formulas and styling, depending on the target.
- Keep workbooks as XLSX or ODS while you work on them, and export CSV only for importing into other systems.
- CSV keeps one sheet and no formulas; converting back will not restore what was dropped.
- Save CSV files as UTF-8 so names with accents and other alphabets survive the trip between programs.
- Before converting a large workbook, remove unused sheets and ranges to keep the result small.
- Name the header row clearly before exporting CSV; most import tools map columns by these names.
- If numbers with leading zeros, such as postcodes or phone numbers, must survive, format those columns as text before converting.
- When a system rejects your file, check whether it expects a comma or a semicolon as the separator; many European systems use semicolons.
Convert CSV files from the command line
LibreOffice converts spreadsheets from the command line without opening a window:
soffice --headless --convert-to xls input.csvThe converter on this page does the same job in your browser, without installing anything.
CSV converter FAQ
What is a CSV file?
CSV stands for Comma-separated values, a spreadsheet format created by no single author; standardised in RFC 4180 in 1972. A CSV file holds a single table as plain text, with commas between values. It has no formatting, formulas or multiple sheets, which is exactly why every program can read it.
How do I open a CSV file?
CSV opens in every spreadsheet program and any text editor. If the program you need will not open it, convert it to a more widely supported format above.
What is the most common CSV conversion?
CSV to XLS is the conversion people search for most. Each line of the CSV becomes a row and each comma-separated value a cell. Numbers are stored as numbers, so they can be summed and sorted in the XLS.
Does converting CSV files here upload them?
Only for some conversions. Converting to HTML, JPG, PDF, PNG uses our conversion server, where the file is deleted as soon as the result is sent back; the other conversions run inside your browser and never leave your device.
Is the CSV converter free?
Yes. There is no sign-up and no watermark. Conversions that use our server accept files up to 25 MB, with a fair-use limit per hour. The site is supported by advertising.
Can I convert CSV files on iPhone or Android?
Yes. Open this page in Safari on iPhone and iPad, or in Chrome on Android, choose your CSV files and download the results to your Downloads folder.
Can I convert several CSV files at once?
Yes. Drop as many as you like; they are converted one after another, each with its own download button.