[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"extension:v3:en:xlsb":3},{"resolvedFromAlias":4,"canonicalExt":5,"ext":5,"name":6,"category":7,"categoryName":8,"updatedAt":9,"popularity":10,"summary":11,"howToOs":12,"quickAnswer":18,"answerIntro":19,"whatIs":20,"description":21,"furtherReading":22,"openInstructions":41,"commonIssues":54,"securityNotes":73,"faq":77,"aliases":90,"mimeTypes":91,"relatedExtensions":93,"breadcrumbs":141,"categoryAnchor":151,"categoryFuturePath":152,"metaDescription":153,"availableHowToOs":154,"openOnDeviceLinks":155,"cannotOpenReasons":171,"cannotOpenFixes":172,"convertOptions":173,"securityAffiliateMessaging":174,"securityAffiliates":175},false,"xlsb","Excel Binary Workbook (BIFF12)","documents","Documents","2026-06-12T08:07:58.782Z",65,".xlsb is Microsoft Excel’s binary workbook format (BIFF12). It opens in Microsoft Excel (Office 2007 and later) and is often used to reduce file size and improve performance for large workbooks.",[13,14,15,16,17],"windows","mac","linux","ios","android","To open .XLSB files on Windows, open Microsoft Excel (Office 2007 or later).","Open a .xlsb file with Microsoft Excel (Office 2007 or later). In Excel, use File > Open and select the .xlsb workbook, or double-click it if Excel is set as the default app.",".xlsb is an Excel workbook stored in a binary file format (BIFF12) defined by Microsoft’s [MS-XLSB] specification. Unlike .xlsx (ZIP + XML), .xlsb stores workbook parts in a binary structure, which can make large spreadsheets smaller and sometimes faster to load/save in Excel.","Excel Binary Workbook (.xlsb) was introduced with Microsoft Office 2007 as part of the Office Open XML era, but it uses a binary representation rather than the XML-in-ZIP approach used by .xlsx. The Library of Congress format description notes it as an Excel binary workbook format introduced with Office 2007 and points to the MS-XLSB specification for technical details.",[23,26,29,32,35,38],{"title":24,"url":25},"IANA Media Types (MIME) registry entry for Excel binary workbook","https://www.iana.org/assignments/media-types",{"title":27,"url":28},"Library of Congress: Microsoft Excel Binary (XLSB) Format","https://www.loc.gov/preservation/digital/formats/fdd/fdd000512.shtml",{"title":30,"url":31},"Microsoft Open Specifications: [MS-XLSB] Excel (.xlsb) Binary File Format","https://learn.microsoft.com/en-us/openspecs/office_file_formats/MS-XLSB/acc8aa92-1f02-4167-99f5-84f9f676b95a",{"title":33,"url":34},"Microsoft Support: File formats that are supported in Excel","https://support.microsoft.com/en-gb/office/file-formats-that-are-supported-in-excel-0943ff2c-6014-4e8d-aaea-b83d51d46247?redirectsourcepath=%252fen-us%252farticle%252ffile-formats-supported-in-excel-for-windows-b3ef04b4-6078-4c0d-b69e-a00ef58f467f",{"title":36,"url":37},"Microsoft Support: Reduce the file size of your Excel spreadsheets","https://support.microsoft.com/en-US/Excel/reduce-the-file-size-of-your-excel-spreadsheets",{"title":39,"url":40},"MICROSOFT OFFICE EXCEL 2007 Binary File Format (.xlsb) Specification (PDF)","https://www.loc.gov/preservation/digital/formats/digformatspecs/Excel2007BinaryFileFormat%28xlsb%29Specification.pdf",{"windows":42,"macos":45,"linux":48,"ios":50,"android":52},[43,44],"Open Microsoft Excel (Office 2007 or later).","Go to File > Open, browse to the .xlsb file, and open it (or double-click the file if Excel is the default).",[46,47],"Open Microsoft Excel for Mac.","Use File > Open and select the .xlsb file.",[49],".xlsb is an Excel-specific binary workbook format; if you cannot open it in your Linux office suite, transfer the file to a system with Microsoft Excel (Office 2007 or later) and open it there.",[51],"If you have access to Microsoft Excel on a desktop (Office 2007 or later), open the .xlsb there; if a mobile app cannot open it reliably, convert it in Excel to .xlsx for easier sharing.",[53],"If the file does not open correctly on mobile, open it in Microsoft Excel on a desktop (Office 2007 or later) and save a copy as .xlsx for broader compatibility.",[55,61,67],{"title":56,"description":57,"steps":58},"Workbook won’t open or shows as an unsupported format",".xlsb is the Excel Binary Workbook (BIFF12) format and is supported in Excel, but older Excel versions or non-Excel tools may not fully support it.",[59,60],"Open the file in Microsoft Excel (Office 2007 or later).","If you need to use another program, open it in Excel first and save a copy as .xlsx.",{"title":62,"description":63,"steps":64},"File is large or slow; need a smaller version for sharing","Large workbooks can be bulky in some formats. Microsoft explicitly suggests saving as .xlsb as one approach to reduce Excel file size.",[65,66],"In Excel, use File > Save As.","Choose “Excel Binary Workbook (*.xlsb)” to create a smaller copy.",{"title":68,"description":69,"steps":70},"Automation/macro safety concerns",".xlsb files are workbooks and can be used in environments where macro-enabled content exists; users may treat them similarly to other Excel files when assessing trust and origin.",[71,72],"Only open .xlsb files from trusted sources, especially if you were not expecting the workbook.","If you must share with others who have stricter policies, consider saving an .xlsx copy without any active content you don’t intend to distribute.",[74,75,76],".xlsb is a binary Excel workbook format; treat unexpected .xlsb attachments as potentially risky content because spreadsheet files can be used as a delivery vehicle in social engineering scenarios.","Because the format is binary (BIFF12), it is harder to inspect manually than XML-based .xlsx; prefer opening untrusted files in a controlled environment and validate the sender before enabling any interactive content.","The format is formally specified by Microsoft ([MS-XLSB]); keep Excel updated to benefit from security fixes in file parsing.",[78,81,84,87],{"question":79,"answer":80},"What program opens .xlsb files?","Microsoft Excel (Office 2007 and later) opens and saves .xlsb (Excel Binary Workbook / BIFF12).",{"question":82,"answer":83},"Why would I use .xlsb instead of .xlsx?",".xlsb stores the workbook in a binary format and is commonly used to reduce file size and improve performance for large workbooks; Microsoft lists it as an option when reducing Excel file size.",{"question":85,"answer":86},"Is .xlsb the same as the old .xls format?","No. .xlsb is the Office 2007-era Excel Binary Workbook format (BIFF12) defined by the MS-XLSB specification; it is distinct from older .xls formats.",{"question":88,"answer":89},"What is the official MIME type for .xlsb?","IANA lists application/vnd.ms-excel.sheet.binary.macroEnabled.12 for Excel binary workbooks (.xlsb).",[],[92],"application/vnd.ms-excel.sheet.binary.macroEnabled.12",[94,100,106,112,118,123,129,135],{"ext":95,"name":96,"category":7,"categoryName":8,"popularity":97,"summary":98,"howToOs":99},"pdf","Portable Document Format",100,"PDF files maintain consistent formatting across devices and are widely used for documents that require a fixed layout, such as forms and reports.",[13,14,15,16,17],{"ext":101,"name":102,"category":7,"categoryName":8,"popularity":103,"summary":104,"howToOs":105},"docx","Microsoft Word Open XML Document",98,"DOCX files are widely used word-processing documents created by Microsoft Word, supporting rich text and multimedia elements.",[13,14,15,16,17],{"ext":107,"name":108,"category":7,"categoryName":8,"popularity":109,"summary":110,"howToOs":111},"xlsx","Microsoft Excel Open XML Spreadsheet",92,"XLSX files are widely-used spreadsheet files that store data, formulas, and charts, and are compatible with various spreadsheet applications.",[13,14,15,16,17],{"ext":113,"name":114,"category":7,"categoryName":8,"popularity":115,"summary":116,"howToOs":117},"log","Plain-text Log File",85,".log files are typically plain-text logs that record events, messages, and errors from software or operating systems. They can usually be opened with basic text editors on any platform.",[13,14,15,16,17],{"ext":119,"name":120,"category":7,"categoryName":8,"popularity":115,"summary":121,"howToOs":122},"pptx","Microsoft PowerPoint Open XML Presentation","PPTX files are widely used for creating and sharing presentation decks with multimedia content.",[13,14,15,16,17],{"ext":124,"name":125,"category":7,"categoryName":8,"popularity":126,"summary":127,"howToOs":128},"txt","Plain Text File",82,"TXT files contain plain text and can be opened on any operating system with a variety of text editors.",[13,14,15,16,17],{"ext":130,"name":131,"category":7,"categoryName":8,"popularity":132,"summary":133,"howToOs":134},"xlsm","Excel Macro-Enabled Workbook (Office Open XML)",75,".xlsm is an Office Open XML Excel workbook that can contain VBA macros. Open it in Microsoft Excel; be cautious because macros can run code.",[13,14,15,16,17],{"ext":136,"name":137,"category":7,"categoryName":8,"popularity":138,"summary":139,"howToOs":140},"ppsx","PowerPoint Show (Office Open XML Slideshow)",70,".ppsx is a Microsoft PowerPoint “Show” file that is designed to open directly in Slide Show mode instead of the normal editing view.",[13,14,15,16,17],[142,145,148],{"label":143,"to":144},"Home","/",{"label":146,"to":147},"File Extension Index","/file-extension",{"label":149,"to":150},".XLSB","/file-extension/xlsb","category-documents","/category/documents","Learn what .XLSB files are, how to open them on every platform, common fixes, and security best practices.",[13,14,15,16,17],[156,159,162,165,168],{"os":13,"label":157,"to":158},"Open .XLSB on Windows","/how-to/open-xlsb-on-windows",{"os":14,"label":160,"to":161},"Open .XLSB on Mac","/how-to/open-xlsb-on-mac",{"os":15,"label":163,"to":164},"Open .XLSB on Linux","/how-to/open-xlsb-on-linux",{"os":16,"label":166,"to":167},"Open .XLSB on iOS","/how-to/open-xlsb-on-ios",{"os":17,"label":169,"to":170},"Open .XLSB on Android","/how-to/open-xlsb-on-android",[56,62,68],[59,60],[],"active_document",[176,180],{"name":177,"description":178,"affiliateUrl":179},"Avast","Avast offers free and premium antivirus software that protects against viruses, malware, ransomware, and phishing. Scan files before opening them to ensure safety.","https://www.avast.com/lp-aff-consumer-store?expid=inf601",{"name":181,"description":182,"affiliateUrl":183},"Norton","Norton 360 delivers comprehensive antivirus protection, VPN, and identity theft monitoring. Scan files for threats before opening to keep your device secure.","http://buy.norton.com/aff_home?utm_campaign=en-ww_nor_n36_aff_nas_nau_nah_cj_nad_low:_sec_nat_mktc_norton_360"]