How to open an XLSB file
An .xlsb file is an Excel binary workbook: the same sheets, rows and formulas as in .xlsx, but written as compact binary code instead of XML text. Someone sent you one and you have no Excel — or Google Sheets and online viewers refuse it. You can open it right in the browser.
Free for personal use. The file is not uploaded to a server — the workbook is parsed in your browser. Windows version — 3.5 MB, no installation: details. Organizations: license.
What XLSB is
XLSB (Excel Binary Workbook) appeared in Excel 2007 alongside .xlsx. From the outside it is the same kind of ZIP archive, but the sheets, shared strings and styles inside are stored not as XML but as binary *.bin files. Excel saves large workbooks this way: the file comes out one and a half to two times smaller and opens faster. Heavy exports from banks, ERP and reporting systems often arrive as .xlsb.
| Format | Inside | Who opens it |
|---|---|---|
.xlsx | ZIP with XML | almost everything: Excel, LibreOffice, Google Sheets |
.xlsb | ZIP with binary records | Excel, LibreOffice; Google Sheets and many viewers do not |
.xls | binary Excel 97–2003 format | see Old .xls files without Excel |
What can open it
- Microsoft Excel 2007 and newer — the native format.
- LibreOffice Calc — opens it, but has to be installed.
- Google Sheets and online converters — most reject .xlsb, and converters ask you to upload the file to somebody else's server. You should not do that with a customer list or a payroll sheet.
- The browser. Drag the file into the app window and the first sheet opens. Nothing is sent anywhere: the workbook is parsed on your computer. After that you get filters, search, sorting, totals and export to Excel .xlsx or CSV.
Sheets, dates and merged cells
The workbook is read the same way as .xlsx: every sheet to choose from (hidden ones marked), dates as dates with the 1904 system taken into account, codes with leading zeros as text, blank rows left in their places. A report title above the header row is skipped automatically, and the value of a merged cell is repeated across the whole area, the way it looks in Excel.
What about formulas
Next to every formula Excel stores the value it calculated on save — that is what you see in the table. The text of the formula itself is not stored in .xlsb: the formula is kept already broken into parts, for Excel's evaluator. If you need to see the formulas, re-save the workbook as .xlsx in Excel or LibreOffice.
FAQ
Can I fix data and save back to .xlsb?
No: .xlsb is opened for viewing. Export the table to .xlsx — that one you can edit and save.
Will a password-protected .xlsb open?
No. A workbook under a password is encrypted as a whole and can only be opened in Excel if you know the password.
Do large workbooks open?
Yes, a sheet up to 384 MB unpacked. The binary format is dense, so that means millions of cells.
Do I need Excel installed?
No — neither Excel nor LibreOffice is needed.
Free for personal use. Your file is not uploaded to a server. Windows version — 3.5 MB, no installation: details. Organizations: license.