XLSX to PDF Converter

The Modern XLSX Format in Business

Since the release of Microsoft Office 2007, the XLSX format has become the primary way to store spreadsheets. Over nearly two decades of existence, it has almost completely replaced the outdated XLS in active business operations. Today, the vast majority of new spreadsheet documents are created in XLSX format — from simple lists to complex financial models with tens of thousands of rows.

The XLSX format is based on the open Office Open XML (OOXML) standard, which was standardized by the International Organization for Standardization as ISO/IEC 29500. This means the format specification is publicly available and can be implemented by any software developer. Thanks to this, XLSX files open not only in Microsoft Excel but also in Google Sheets, LibreOffice Calc, Apple Numbers, and dozens of other spreadsheet applications.

Despite the universality of XLSX, when distributing documents to external recipients, there's often a need to convert to PDF. Reasons vary: protecting data from editing, guaranteeing identical display on any device, corporate policy requirements, or document management standards. The PEREFILE service allows you to perform this conversion quickly and for free through a browser without installing software.

Office Open XML Format Architecture

Understanding the internal structure of XLSX helps appreciate what happens during conversion to PDF and which document elements are preserved.

XLSX File Structure

An XLSX file is a ZIP archive with a specific folder and XML file structure inside. If you rename the .xlsx extension to .zip and unpack the archive, you can see the following contents:

• [Content_Types].xml — description of content types in the archive
• _rels/ — folder with relationship files between components
• docProps/ — document properties (author, creation date, title)
• xl/ — main folder with workbook contents
  • workbook.xml — workbook structure description (sheets, names)
  • worksheets/ — folder with sheets (sheet1.xml, sheet2.xml...)
  • sharedStrings.xml — shared pool of text strings
  • styles.xml — formatting styles
  • charts/ — charts
  • drawings/ — graphic objects

This modular architecture makes the format resistant to partial damage — if one component is corrupted, the remaining data can be recovered. During conversion to PDF, all these components are combined into a single visual document.

Modern Format Capabilities

XLSX significantly exceeds its predecessor in technical specifications:

Modern analytical tasks — processing customer databases, financial modeling, statistical analysis — often require data volumes exceeding the limits of the old format. XLSX allows working with a million rows in one file, which is critical for business analytics and data science.

Benefits of Presenting Data in PDF

Converting XLSX to PDF pursues specific goals that determine the choice of this approach to distributing tabular data.

Document Immutability

PDF fixes the document state at creation time. Unlike XLSX, where formulas recalculate, links update, and content is easily editable, PDF remains static. This is critical for:

• Legally significant documents — contracts with calculation attachments, work completion acts
• Financial reporting — approved budgets, closed periods
• Approved versions — documents that have passed the approval cycle
• Audit documents — data fixation as of a specific date

The PDF recipient sees the document exactly as the sender created it, without the possibility of accidental or intentional number changes.

Universal Compatibility

PDF opens on any modern device:

• Desktop computers — Windows, macOS, Linux
• Mobile devices — iOS, Android
• Web browsers — built-in viewing without additional software
• E-readers — many readers support PDF

Viewing XLSX requires Microsoft Excel, its equivalent, or a web application. PDF opens in any browser directly from email attachments or cloud storage.