What happens when you convert CSV to XLS
- 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.
- XLS allows at most 65,536 rows and 256 columns per sheet. Larger sheets do not fit the format; use XLSX for them.
- The file is read by SheetJS running in your browser; nothing is uploaded.
How to convert CSV to XLS online
- Press "Choose CSV files" and select one or more files, or drag them onto the box. You can add files of any size your device can hold in memory.
- There are no settings to choose: the converter keeps everything the target format can hold.
- Press "Convert to XLS". The spreadsheet library, about 900 KB, loads the first time and then workbooks convert in a moment.
- Save each XLS with its download button. Close the tab and every trace of the files is gone from memory.
Why convert CSV to XLS?
CSV files usually come from data exports, imports into databases and exchanging tables between programs. People convert them to XLS because some older accounting systems, government portals and legacy software still only accept the older XLS format from Excel 97 to 2003.
In short, CSV is good at what it was made for, and XLS is the more practical choice when the file has to open, upload or print somewhere else. CSV opens in every spreadsheet program and any text editor, while XLS opens in Excel, Google Sheets, Numbers and LibreOffice Calc.
How to convert CSV to XLS on Windows, Mac, iPhone and Android
On Windows
Open this page in Chrome, Edge or Firefox, drag your CSV files in from File Explorer, and press Convert. Each XLS is saved to your Downloads folder.
On a Mac
Safari, Chrome and Firefox all work. Drag the CSV files from Finder onto the drop zone and the XLS files land in Downloads.
On iPhone and iPad
Open the page in Safari and tap Choose CSV files. You can pick from Photos or from the Files app. The converted XLS appears in Files, in the Downloads folder.
On Android
Open the page in Chrome, tap Choose CSV files and pick them from Files or your gallery. The XLS is saved to the Download folder, where any file manager can find it.
Best settings for CSV to XLS
There are no settings to choose: the CSV is read cell by cell and written as a legacy Excel 97 to 2003 workbook.
Check the result in your spreadsheet program before deleting the original: formulas are carried over, but charts, images and styling are not, so a heavily formatted report will look plainer.
CSV vs XLS: the differences
| CSV | XLS | |
|---|---|---|
| Full name | Comma-separated values | Excel 97 to 2003 workbook |
| Type | spreadsheet | spreadsheet |
| Created by | no single author; standardised in RFC 4180 | Microsoft |
| First released | 1972 | 1997 |
| Compression | Lossless | Lossless |
| What it holds | one table of plain text values, one row per line | several sheets with values, formulas and formatting in a binary file |
| In a browser | opens in every spreadsheet program and any text editor | opens in Excel, Google Sheets, Numbers and LibreOffice Calc |
| Common uses | data exports, imports into databases and exchanging tables between programs | older Excel files and systems that still export the legacy format |
| MIME type | text/csv | application/vnd.ms-excel |
About CSV and XLS files
What is a CSV file?
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.
What is an XLS file?
XLS is the binary Excel format used before 2007. It is limited to 65,536 rows and 256 columns per sheet, far fewer than XLSX allows.
CSV to XLS not working? Common problems
- The file will not open. Password-protected workbooks are encrypted, so they cannot be read without the password; remove the password in Excel first.
- Dates look like numbers. Spreadsheets store dates as numbers underneath; apply a date format to the column in your spreadsheet program.
- Special characters look wrong in Excel. The CSV is UTF-8; in older Excel, use Data, From Text/CSV and choose UTF-8 instead of double-clicking the file.
Convert CSV to XLS 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 to XLS converter FAQ
Will I lose quality converting CSV to XLS?
Cell values and formulas are kept exactly. Charts, images and cell styling are not.
Why is the XLS a different size from the CSV?
Workbook formats differ in how they compress, so the XLS may be a little larger or smaller than the CSV.
Are my CSV files uploaded anywhere?
No. The conversion runs inside this browser tab using the open-source SheetJS library, so your files stay on your device. You can disconnect from the internet after the page and converter engine have loaded and it still works.
Can I convert several CSV files to XLS at once?
Yes. Select or drop as many files as you like; they are converted one after another and each gets its own download button.
How do I open an XLS file?
XLS opens in Excel, Google Sheets, Numbers and LibreOffice Calc. XLS is common for older Excel files and systems that still export the legacy format.
Is this CSV to XLS converter free?
Yes. There is no sign-up, no watermark and no limit on how many files you convert. The site is paid for by advertising, and because conversions run on your device there is no server cost per file.
Can I convert CSV to XLS on my phone?
Yes. The converter works in Safari on iPhone and iPad and in Chrome on Android. Converted files are saved to the Downloads folder.