XLSX to XLS Converter
Processing entirely on your device — large files may take a moment.
Excel Spreadsheet and Excel 97-2003 Workbook exist for different jobs: XLSX is the modern Microsoft Excel workbook format. It stores multiple sheets with values, styles and charts, and opens in Excel, WPS Office, Numbers and Google Sheets. Opening legacy .xls exports in modern tools is easiest after converting them to XLSX or CSV.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How XLSX compares to XLS
| XLSX | XLS | |
|---|---|---|
| Structure | Multiple sheets | Multiple sheets (BIFF8) |
| Types / schema | Typed cells + formulas | BIFF8 typed cells |
| Compatibility | Excel 2007+, LibreOffice, Sheets | Legacy Excel systems |
| Best for | Finance, analysis, models | Reading historical workbooks |
How to convert XLSX to XLS
- 1
Select your files
Drag & drop your XLSX files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to XLS". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted XLS file individually, or grab everything at once as a ZIP archive.
About the XLSX format
XLSX is the modern Excel workbook (default since Excel 2007, same OOXML zip-package idea as DOCX). One file can carry multiple sheets, typed cells, formulas that recalculate, charts, conditional formatting and pivot caches — a small application, not just a table. LibreOffice, Google Sheets and WPS open it natively, and server-side libraries can read and write it without Excel installed.
Being a spreadsheet program's file, it is a poor plain-data exchange format: formulas reference cell positions that break when rows are reordered, hidden sheets and cached values surprise consumers, and the zip package is heavier than CSV. For analysis and finance it is the right tool; for pipelines, export the CSV.
+Strengths
- ✓Multi-sheet with formulas, charts and formatting
- ✓Typed cells and recalculation
- ✓Opens natively across the office ecosystem
!Limitations
- −Heavier and less diff-friendly than CSV
- −Formulas tie data to cell positions
- −Hidden state (sheets, caches) surprises downstream tools
About the XLS format
XLS is the legacy Excel binary format (BIFF8, Excel 97–2003). It does everything its era supported — sheets, formulas, formatting, VBA macros — under hard limits: 65,536 rows and 256 columns per sheet. Millions of government, banking and manufacturing templates were built on it, which is why it still arrives in inboxes.
There is no reason to create new XLS files: XLSX handles everything better with no row ceiling. The realistic use case is reading — opening or converting historical files, or feeding systems whose import filters predate 2007.
+Strengths
- ✓The only format ancient Excel-era systems accept
- ✓Full BIFF8 feature set: formulas, macros, formatting
!Limitations
- −65,536-row and 256-column ceiling per sheet
- −Obsolete binary spec, awkward for modern tools
- −Macro-enabled files carry security risk
Why convert XLSX to XLS?
Converting makes sense where the strengths of XLS meet what XLSX cannot give you. The only format ancient Excel-era systems accept Meanwhile Heavier and less diff-friendly than CSV One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this XLSX to XLS converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
What about special characters and non-English text?
Everything is handled as UTF-8. When you export CSV for Excel, a UTF-8 BOM is included automatically so Chinese, Japanese, Korean and accented characters display correctly on both Windows and macOS.
Is my data safe here?
Yes. The conversion is plain JavaScript running in your tab: the data is parsed and re-serialized in memory, never sent anywhere, and disappears when you close the page.
How large can my XLSX file be?
Since everything runs locally in your browser, the real limit is your device memory rather than an upload cap. Files up to a few hundred megabytes are usually fine on a modern computer; extremely large ones simply take longer.