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Convert XLS to XLSX Online


CONVERT XLS to XLSX ONLINE

1) Upload XLS file to convert

 

Drop files here, or Click to select
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Allowed file types: fasta, qif, ofx, iif, srt, ics, excel, ris, bib, ods, xls, xlsx, xlsm, csv, tsv, tab, xlsb, xltx, xlr, pxl, qpw, wb3, wq1, dbf, wk3, 123, mdb, evtx, pages, numbers, sqlite

2) Set converting XLS to XLSX options

Convert to

 

Options

Header:
Footer:

3) Get converted file

DOWNLOAD CONVERTED FILE
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Get Total Excel Converter to convert XLS, XLSX, ODT, XLSM, etc. safely.

Excel Converter To Convert Spreadsheets
  • Convert Excel Files in Batch!;
  • Convert XLS to XLSX and in many other formats
  • Convert hundreds of spreadsheets in 3 clicks;
  • Both MS Office and OpenOffice files;
  • Have a desktop converter that works without Internet;
  • Keep your files safe, don't send them to the web;
  • Get more accurate results with the more poweful engine.
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close Total Excel Converter
okTotal Excel Converter supports almost all Excel extensions: XLS, XLSX, XLSM, XLSB, XLT, XLTM, XLTX, XLK, XLW. When the new Office is released, we will add new file types too.
okWith Total Excel Converter you can convert Excel to PDF and add a digital signature in one go.
okTotal Excel Converter can convert each page of your spreadsheet into a separate file.
okTell Total Excel Converter to copy original time stamps if you don't want to change the date.
okHave an outdated Microsoft Office 2003? Update all your old files to the new format in one go. Convert XLS files to XLSX in batches.
okTotal Excel Converter will help you to convert Excel 2003 XML Files (rare option!)
okTotal Excel Converter has a built-in renamer to give your files new descriptive names. Include a counter, a date or worksheet name into the file name and your files will be in perfect order.
okConvert Excel spread sheets via our most straightforward interface.
okThe widest list of output file types: DOC, PDF, HTML, MHT, XHTML, CSV, TXT, TIFF, JPEG, SVG, RTF, XML, XLS, XLSX, ODS, ODT, Lotus, DIFF, SYLK, LATEX, SQL, DBF, Access!
okTotal Excel Converter can combine several Excel spread sheets into one TIFF or PDF file.
okWant to quickly find a file? Total Excel Converter helps you to preview any document you select.
okAdd your logo or any other image to the header or the footer of the output file.
okWant more order? Add page counters or a date to every page of the output files. Sequential numbering of several folders is avaialble.
okTotal Excel Converter can copy original time stamps if you want to keep them.
okWhen you convert Excel to PDF you can set user permissions, password-protect your files or sign with a digital signature. Get PDF, PDF/A and non-searchable PDFs.
okTotal Excel Converter can be run via command line (get the ready-to-use command line from GUI).

How to convert XLS to XLSX?

1

💾 Upload Your File: Go to the site, click on «Upload File,» and select your XLS file.

2

✍️ Set Conversion Options: Choose XLSX as the output format and adjust any additional options if needed.

3

Convert and Download: Click 👉«Download Converted File»👈 to get your XLSX file.

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Cloud Based
There is no need to install any software to convert XLS to XLSX with CoolUtils. Simply access the internet, and you can easily convert your file online with our service.
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Our hardware operates in top-tier, highly secure data centers equipped with advanced electronic surveillance and multi-factor access control systems.
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Ease of Use
Converting XLS to XLSX online has never been so simple. Drop your legacy Excel 97-2003 workbook and the converter produces a modern XLSX file — formulas, charts, named ranges, and cell styles preserved, full compatibility with current Excel, LibreOffice, and Google Sheets. No legacy Office required.
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XLS File

File extension .XLS
CategoryDocument File
DescriptionXLS is the most popular format for storing table data. It is native Microsoft Excel format with data stored in numbered cells that form columns and rows. The top line and left column of each table contains numbering of each cell that can contain either static or dynamic data that is calculated from formulas. XLS features powerful calculation and charts-building options, as well as rich text formatting. XLS is compatible with numerous table editors such as Calc, PlanMaker, OpenOffice, etc.
Associated programsMicrosoft Excel
Microsoft Excel Viewer
OpenOffice
Developed byMicrosoft
MIME typeapplication/vnd.ms-excel
Useful linksMore detailed information on XLS files
Conversion typeXLS to XLSX

XLSX File

File extension .XLSX, .EXCEL
CategoryDocument File
DescriptionXLSX is a format from Office Open XML family, a native MS Excel file type starting from version 2007. As opposite to XLS, this format uses ZIP compression that makes XLSX files smaller in size. Actually XLSX file is an archive of XML-documents. The cells in XLSX table can contain plain text, formulas or graphic elements. XLSX can be read in MS Office 2007 and later, Universal Viewer, OpenOffice, MS Office Excel Viewer, Corel WordPerfect Office. This format doesn’t support macros.
Associated programsMicrosoft Excel 2007
OpenOffice
OxygenOffice Progessional (Linux)
Developed byMicrosoft
MIME type
Useful linksMore detailed information on XLSX files
5 star2026-02-11
Upgraded 800 legacy XLS spreadsheets from our ERP migration to XLSX in a single batch run. Formulas, named ranges, and formatting all transferred correctly.
Miroslava Horáčková
4 star2026-04-01
Modern Excel add-ins we rely on only work with XLSX files. Converting our old template library took minutes and eliminated the compatibility warnings we had been ignoring for years.
Samuel Oduya
5 star2026-05-16
Reduced file corruption risk in our finance team by migrating all XLS templates to XLSX. The converter handled pivot tables and macros without stripping them out.
Zhen Wei

Rating XLS to XLSX   5 star XLS to XLSX   4.7 (870 votes)
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Convert XLS to XLSX — Frequently Asked Questions ▼

Will my formulas still work after converting XLS to XLSX?

Yes. Standard Excel formulas convert correctly. The XLSX format supports all formulas that XLS supports, plus additional functions introduced in Excel 2007 and later. Complex array formulas and named range references are preserved. Verify calculated cells after conversion to confirm results match the original.

Will macros (VBA) be preserved in the XLSX?

No. XLSX is the macro-free format by design. If your XLS file contains VBA macros, they will not be included in the XLSX output. To preserve macros, you need XLSM (macro-enabled workbook). The online converter outputs standard XLSX without macro support.

Is there any data loss when converting from XLS to XLSX?

For standard spreadsheet content — values, formulas, formatting, charts, and tables — there is no data loss. The risk area is VBA macros (dropped in XLSX) and some legacy XLS-specific formatting quirks that have no XLSX equivalent. Always open and verify the converted file before discarding the XLS original.

Why is my XLSX file smaller than the XLS?

XLSX stores data as XML inside a ZIP container, which compresses repetitive text very efficiently. XLS stores data as an uncompressed binary structure. For most workbooks, the XLSX is 30-60% smaller than the equivalent XLS. This makes XLSX better for email, SharePoint, and storage.

Can Google Sheets open XLS files directly?

Yes, but complex XLS files sometimes display incorrectly in Google Sheets — particularly pivot tables, certain chart types, and advanced conditional formatting. Converting to XLSX first often resolves these issues, since XLSX is the format Google Sheets was designed to import.

Is there a file size limit for the online converter?

The online converter accepts XLS files up to 50 MB. For larger files or bulk conversion of multiple workbooks, use Total Excel Converter on the desktop, which has no size limit.

How do I convert hundreds of XLS files to XLSX in one operation?

Use Total Excel Converter on the desktop: TotalExcelConverter.exe C:\xls_archive C:\xlsx_output /ConvertTo xlsx /ProcessRecursively. It processes entire folder trees and supports scheduling via Windows Task Scheduler. A 30-day free trial is available at coolutils.com/TotalExcelConverter.
 

 

Convert XLS to XLSX Online

Finance teams and administrators convert XLS to XLSX to modernize legacy spreadsheets so they work reliably in current Excel versions and integrate with modern data tools.

What Is XLS?

XLS is Microsoft Excel's binary format from the 1997-2003 era. It uses a proprietary BIFF (Binary Interchange File Format) structure that is fully understood only by Excel itself. XLS has hard limits: 65,536 rows, 256 columns, and 4,000 unique cell formats. Modern Excel, Google Sheets, and LibreOffice still open XLS but generate compatibility warnings and may misrender complex files.

What Is XLSX?

XLSX is the Office Open XML format introduced with Excel 2007 and standardized as ISO/IEC 29500. It stores spreadsheet data as compressed XML, supports over 1 million rows, and is the default format for all modern spreadsheet applications. XLSX integrates cleanly with Power Query, Power BI, Python libraries (openpyxl, pandas), and cloud tools.

Online Converter vs Desktop Converter

FeatureOnline (this page)Total Excel Converter (desktop)
Batch conversion✓ Single file✓ Entire folders, recursive
File size limitUp to 50 MBNo limit
Automation / scripting✗✓ Command-line, .bat, Task Scheduler
Files stay local✗✓ No upload required
PriceFreeFrom $29.90

Batch CLI example: TotalExcelConverter.exe C:\xls_files C:\xlsx_output /ConvertTo xlsx /ProcessRecursively

How to Convert XLS to XLSX

  1. Click Choose File and select your .xls file
  2. The format is detected automatically
  3. Select XLSX as the output format
  4. Click Convert — processing takes a few seconds
  5. Click Download to save your XLSX file
  6. Open in Excel, Google Sheets, or LibreOffice and verify formulas and formatting

When Do You Need XLS to XLSX?

Feature Online Converters CoolUtils Desktop Excel Built-in Other Software
Batch Conversion Limited ✅ Unlimited Manual only Limited
File Size Limit 1-5MB ✅ No limits System dependent Varies
Privacy & Security Upload required ✅ 100% offline ✅ Local only Varies
Conversion Speed Internet dependent ✅ Fast local processing Slow Medium
Advanced Options Basic ✅ Full customization Limited Basic
Cost Free/Premium One-time purchase Requires Office Subscription
Formatting Preservation Good ✅ Excellent Good Varies
Multiple Formats Support Limited ✅ 40+ formats Few formats Limited

Convert from XLS

Using CoolUtils, it is possible to convert XLS files to a variety of other formats:

Convert to XLSX

Using CoolUtils, it is possible to convert a variety of other formats to XLSX files:

                                                                                                 

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