XLS File Format

Excel 97-2003 Workbook category

XLS is the classic Excel 97–2003 workbook format, still produced by many banks, ERP systems and export tools.

Typical use: Opening legacy .xls exports in modern tools is easiest after converting them to XLSX or CSV.

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

Structure: Multiple sheets (BIFF8)
Types / schema: BIFF8 typed cells
Compatibility: Legacy Excel systems
Best for: Reading historical workbooks

Convert XLS to…

10 direct directions plus 1 workflows, sorted A–Z; 🔥 marks popular targets.

XLS to CSV Hot XLS to HTM Hot XLS to HTML Hot XLS to JSON Hot XLS to MHT XLS to TSV XLS to XHTML XLS to XLSM XLS to XLSX Hot XLS to XLTX

Cross-engine workflows

XLS to PDF

Frequently asked questions

What is a XLS file?

XLS is the classic Excel 97–2003 workbook format, still produced by many banks, ERP systems and export tools.

How do I convert XLS files online?

Pick a target format from the "Convert XLS to…" list below, drop your file and hit convert. Everything runs in your browser — no install, no upload, no watermark, no limits.

Is it safe to convert XLS files here?

Yes. Every conversion is performed by your own device inside the browser — files never leave for a server, and the page keeps working even offline.

Which formats can XLS convert to?

This page lists all 11 directions across documents, images, audio, video, spreadsheets and archives — each one is its own free converter page.