Why convert XLS to XLSX
The .xls format was Excel’s default from 1997 to 2003. Excel still opens it, but in Compatibility Mode, with limits from that era. Converting to .xlsx removes those limits:
| XLS (Excel 97–2003) | XLSX (Excel 2007 and later) | |
|---|---|---|
| Rows per sheet | 65,536 | 1,048,576 |
| Columns per sheet | 256 | 16,384 |
| File structure | One binary file | Compressed XML files in a ZIP |
| Compression | None | Built in, so large sheets are usually much smaller |
| Opens in Google Sheets, Numbers, LibreOffice | Yes | Yes, and more reliably |
Some online services, import tools and newer apps no longer accept .xls at all, which is the most common reason people need this conversion.
How to use it
- Choose your
.xlsfiles or drop them on the box above. You can add several at once. - Each workbook is converted on your device in a second or two.
- Download the
.xlsxfiles, or all of them together as a ZIP.
What comes across, and what doesn’t
The converter reads the workbook’s data, not its appearance. That makes it reliable for what usually matters in an old spreadsheet:
- Kept: every sheet and its name, cell values, text in any language, formulas, merged cells, number and date formats, column widths and hidden sheets.
- Not kept: cell colours, fonts and borders, charts, pictures, comments, data validation lists, pivot tables and macros.
If the look of a workbook matters, for example a formatted invoice template, open it in Excel and use File › Save As › Excel Workbook (.xlsx). That keeps everything Excel supports. This tool is for when you don’t have Excel to hand, or have a folder of old data files to bring up to date.
Old files in other languages
Very old .xls files were sometimes saved in a regional character set rather than Unicode, such as Cyrillic or Japanese encodings. The converter includes those code pages, so names and text come across correctly instead of turning into question marks.
Privacy
Spreadsheets often hold salaries, customer lists or accounts. The workbook is read by SheetJS, an open-source spreadsheet library, running inside your browser. Nothing is uploaded: once you’ve converted one file, the converter keeps working even with your internet connection switched off.
Questions
Is the formatting kept?
Partly. Values, formulas, merged cells, number formats (dates, currency, percentages) and column widths are kept. Fonts, fill colours, borders, charts, images and conditional formatting are not, so a plain data sheet converts cleanly while a heavily styled report will look plainer.
Will my formulas still work?
Yes. Formulas are stored as formulas, not just their results, and Excel recalculates them when you open the new file.
What happens to macros?
They are left out. An .xlsx file can't contain macros by design. If you need them, open the .xls in Excel and use File › Save As › Excel Macro-Enabled Workbook (.xlsm) instead.
My file is password-protected. Can it be converted?
Not here. Open it in Excel with the password, remove the protection, save, and then convert it. The converter never tries to break passwords.
Last reviewed 3 November 2026