What is an XLSB file?

Spreadsheets are a cornerstone of modern data management, used for everything from financial analysis to scientific research. While most users are familiar with common formats like XLSX or CSV, there’s another lesser-known format that offers powerful performance advantages—XLSB.

In this article, we’ll take a closer look at the technical foundations of XLSB, its practical use cases, pros and cons, and how to open and edit these files.

Technical overview

The XLSB (Excel Binary Workbook) file format was introduced with Microsoft Excel 2007 as part of the broader Office Open XML (OOXML) standard. However, unlike XLSX, which uses a ZIP-compressed collection of XML files to store spreadsheet content, XLSB stores everything—including cell values, formulas, charts, and formatting—as compact binary data. This binary representation allows software to read and write information much faster than the XML-based XLSX format.

Because binary data is denser and doesn’t require parsing large text-based structures, operations like loading the workbook, recalculating formulas, filtering rows, and saving changes are significantly faster. This is particularly noticeable with files that contain:

• High volumes of numerical data
• Arrays and matrix formulas
• Extensive conditional formatting
• Pivot tables and data connections
• VBA projects or embedded objects

XLSB files also handle compression more effectively due to the reduced size of binary data compared to verbose XML. In benchmarks, binary workbooks can be up to 50% smaller and 2–3x faster to open and save than their XLSX equivalents, depending on the contents.

However, this performance comes at a cost: the file format is less transparent. Unlike XML files, which can be unzipped and manually examined or repaired, XLSB files require specialized software to access or debug the contents. This makes the format powerful but less accessible for manual recovery or third-party integrations that rely on open standards.

Overall, XLSB is a high-performance alternative to traditional spreadsheet formats, optimized for speed, size, and intensive data operations, especially when working with large and complex workbooks.

Typical use cases

As we said before, XLSB files are best suited for scenarios where speed and processing efficiency take priority over wide compatibility or long-term portability. This makes them a practical choice in professional environments where large and complex spreadsheets are part of daily workflows. For example, in financial modeling, analysts often work with massive datasets that include thousands of rows, multiple worksheets, and nested formulas—situations where fast loading and recalculation are critical. Similarly, business intelligence reports, especially those powered by dynamic pivot tables and advanced formula logic, benefit from the performance gains offered by the binary format.

In scientific research, where experiments may generate large volumes of structured data requiring rapid updates and computations, XLSB can dramatically reduce lag and improve productivity. Another key use case is in automated tools built with VBA (Visual Basic for Applications). Since XLSB supports macros natively, it’s ideal for creating spreadsheets that include custom functions, automation scripts, and interactive forms. In all these scenarios, the XLSB format helps streamline workflows and optimize performance, even though it may require more care when sharing files or working across different software platforms.

Pros and cons of XLSB files

Pros

• High performance: Reading and writing binary data is faster, improving calculation speed and file operations.
• Smaller file size: XLSB reduces storage needs, especially for large and complex workbooks.
• Native macro support: Unlike XLSX, which requires XLSM for macros, XLSB supports them directly and efficiently.

Cons

• Not human-readable: The binary structure makes it difficult to inspect or recover data manually if the file is corrupted.
• Limited compatibility: Some older or third-party applications may not support XLSB, favoring standard XML-based formats.

How to open XLSB files

Although XLSB files are typically associated with a specific proprietary environment, there are alternative tools that support this format effectively. One of the most reliable options is ONLYOFFICE Docs.

ONLYOFFICE Docs offers a modern, secure, and collaborative environment for working with documents. It supports a wide range of formats, including XLSB.

Opening XLSB files with ONLYOFFICE

You can open XLSB files directly in the editor, just like any other spreadsheet. Simply double-click the file from your computer or connected storage, and it will open with full support for layout, formatting, and formulas, making it easy to view and edit.

ONLYOFFICE provides a familiar spreadsheet environment with full support for cell formatting, data types, and formulas. The software ensures smooth editing and lets you save your changes directly in the original XLSB format.

Get ONLYOFFICE and open XLSB files with ease

Open XLSB files with ease—whether online by creating a free ONLYOFFICE DocSpace account or offline by downloading the free desktop app for Windows, Linux, or macOS.

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