XLS → XLSX
Upgrades legacy XLS (BIFF8) to XLSX (OOXML), migrating pre-2003 spreadsheets into modern Office environments.
Drag files here or click to upload (multiple files supported)
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How to convert XLS to XLSX
- 1Upload your XLS file by dragging, clicking, or pasting.
- 2Adjust quality settings if needed.
- 3Click 'Convert Now' and wait for the conversion to complete.
- 4Download your converted XLSX file.
About XLS to XLSX conversion
XLS is the binary BIFF8 format for Excel 97-2003, with a row limit of 65536 per single worksheet, and is a common legacy format for early office systems. XLSX is an ISO standard Open XML format launched in 2007, which uses ZIP to encapsulate XML structures. It is the default format for Excel 2007 and later versions, and conversion can break through the row limit of the XLS format.
This conversion is processed based on SheetJS, retains all worksheets in the input file, extracts cached calculated values of original formulas, automatically infers cell data types, and fully preserves header information. The generated XLSX file after conversion is usually smaller than the original XLS file with the same content.
This conversion is suitable for adapting files generated by old Excel to Excel 2007 and later versions, and can also meet the import requirements of modern spreadsheet software such as WPS Office and Google Sheets. It can be used to solve the problem of insufficient compatibility of output files from legacy systems.
XLS vs XLSX: technical comparison
| Feature | XLS | XLSX |
|---|---|---|
| Released | 1987 | 2007 |
| Developer | Microsoft | Microsoft / ECMA-376 |
FAQ about XLS → XLSX
Does table quality change after conversion
There is no quality loss to table content. Original cell content, formatting and worksheet structure are all fully preserved. The conversion tool only completes format encapsulation migration.
Are multiple worksheets from the original file preserved
All worksheets contained in the input XLS file are fully preserved in the output XLSX file, and no existing worksheets are automatically deleted or merged.
What is the single file size limit
The maximum single file size for this service on this site is 50MB, and only one file can be converted at a time. Files exceeding the limit cannot be submitted for processing.
Are uploaded files stored
Files are uploaded to the server via HTTPS for conversion. After conversion is complete, the server immediately deletes both the source file and the output file, and does not store any files.