XLS to XLSM Converter
Processing entirely on your device — large files may take a moment.
Excel 97-2003 Workbook and Excel Macro-Enabled Workbook exist for different jobs: XLS is the classic Excel 97–2003 workbook format, still produced by many banks, ERP systems and export tools. Convert XLSM workbooks to CSV, JSON or Parquet exactly like XLSX — the cell data is identical.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How XLS compares to XLSM
| XLS | XLSM | |
|---|---|---|
| Structure | Multiple sheets (BIFF8) | Multiple sheets |
| Types / schema | BIFF8 typed cells | Typed cells + formulas |
| Compatibility | Legacy Excel systems | Excel 2007+, LibreOffice, Sheets |
| Best for | Reading historical workbooks | Finance, analysis, models |
How to convert XLS to XLSM
- 1
Select your files
Drag & drop your XLS 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 XLSM". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted XLSM file individually, or grab everything at once as a ZIP archive.
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
About the XLSM 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
Why convert XLS to XLSM?
There is a concrete reason this conversion exists: 65,536-row and 256-column ceiling per sheet XLSM sidesteps that — Multi-sheet with formulas, charts and formatting If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this XLS to XLSM 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 XLS 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.