XLS to XLSX
Excel 97-2003 to modern .xlsx, long numbers kept as text
Drag & drop files here
or browse files
Supports .xls (Excel 97-2003); .xlsx / .csv can be re-saved too
About this tool
Legacy systems, banks and government portals still export .xls (Excel 97-2003) while modern tools increasingly require .xlsx (16x more rows per sheet, better compression). This tool rewrites every worksheet into modern Open XML with SheetJS - structure and values intact.
Honest scope: values and structure are reliable; 2003-era visual styling, macros and legacy charts are not migrated. Long IDs are written as text so nothing loses precision. For the reverse direction use XLSX to XLS. Everything runs locally - nothing is uploaded.
Features
- Every worksheet rewritten to .xlsx, structure intact
- Long IDs written as text - no precision loss
- Past the .xls ceiling of 65,536 rows / 256 columns
- Fully local processing - no upload, no limits
How to use
- Drop in your .xls file (.xlsx / .csv also accepted)
- Click Convert
- Download the generated .xlsx
Frequently asked questions
- Will data be lost in conversion?
- Data, sheet structure and formula values are fully preserved. What is not migrated: 2003-era visual styling, VBA macros and legacy charts - mostly obsolete in the new format anyway. Long IDs are written as text so every digit survives.
- Why switch to .xlsx at all?
- 16x the row limit (1,048,576), far smaller files (zip-compressed), better support for modern functions and cloud platforms. Legacy .xls only makes sense when the recipient literally cannot accept .xlsx.
- Batch conversion?
- This page processes one file at a time (conversion is milliseconds; drop files one after another). Use Excel Merge to combine multiple files into one workbook, or XLSX to XLS for the reverse direction.
- Is the file uploaded?
- No - SheetJS runs in your browser and the file never leaves the device.