What data actually gets cut when saving down to XLS?

Everything outside the old grid: rows past 65,536 and columns past IV (the 256th) do not exist in XLS and are dropped. Within the grid, values and classic formulas survive - check row counts after converting anything tall.

What happens to XLOOKUP, LET, and dynamic array formulas?

They have no representation in the 97-2003 format, so they arrive as error values or as their last computed results - either way the live formula is gone. Rewrite critical logic with classic functions like VLOOKUP or INDEX/MATCH before converting if the file must stay functional.

Do pivot tables and slicers survive the downgrade?

Pivot tables mostly work in a reduced, old-style form; slicers, sparklines, and icon-set conditional formats postdate XLS and are removed. Opening the converted file in Excel and running the Compatibility Checker gives a full inventory.

XLSX to XLS Converter – Free & Online

Convert XLSX to XLS

Turn XLSX files into XLS in seconds — free, secure, and no signup required.

Free tier: 5 conversions/day, files up to 50 MB, ad-supported. Need more? See Pro plans →

256-bit SSL encryptionYour files are protected end-to-end

Lightning-fast conversionsProcess files in seconds, not minutes

All major document formatsPDF, DOC, DOCX, XLS & more

No registration requiredStart instantly — 5 free conversions a day

Files auto-deleted in 1 hourGDPR-friendly: we never keep your files

Downgrade a modern Excel XLSX workbook to the legacy XLS format so it opens in Excel 97-2003 and old systems that predate OOXML. The downgrade is real: anything relying on post-2007 capabilities is trimmed to fit the older container.

Convert XLSX to XLS – Free Online XLSX to XLS Converter

Why convert XLSX to XLS?

Exchange files with Excel 97-2003 installs, which cannot read XLSX without the long-retired Compatibility Pack.
Satisfy upload portals, ERP importers, and instruments hard-coded to expect .xls.
Test how a workbook degrades under old-format constraints before it ships to a legacy environment.

Tip: Rows beyond 65,536 and columns beyond IV (the 256th) are cut, and functions XLS never knew - XLOOKUP, LET, dynamic arrays - break or freeze to values. Big or modern workbooks should expect losses.

How to convert XLSX to XLS

Upload your XLSX file using the area above.
XLS is preselected as the target format.
Click Start and wait for the conversion to finish.
Download your converted XLS file.

Convert XLSX to XLS

Convert XLSX to XLS – Free Online XLSX to XLS Converter

Why convert XLSX to XLS?

How to convert XLSX to XLS

XLSX to XLS — Frequently Asked Questions