XLSB to XLSX Converter
Convert Excel binary workbooks (.xlsb) into standard .xlsx files that every spreadsheet tool can open.
Drop your files here or click to upload
Supports .xlsb · up to 50MB · or paste a file from your clipboard
How to Convert XLSB to XLSX
- Drop in your .xlsb - or several at once, which converts them as a batch and returns a ZIP.
- Let it parse - the binary worksheet records are decoded and a standard Open XML workbook is written, all inside the page.
- Download - the output keeps the original name with an .xlsx extension.
What the two formats have in common, and where they differ
Both are ZIP archives with the same internal layout: a workbook part listing the sheets, a shared string table, a styles part, and one part per worksheet. The difference is that .xlsx stores each worksheet as XML and .xlsb stores it as a compact stream of typed binary records. Excel does not have to serialise and reparse XML for every cell, which is where the speed and the size advantage come from - and why almost nothing outside Excel reads the format.
Converting is therefore a genuine rewrite: the records are decoded to values and formulas, then written back out as XML.
What crosses over
| Carried into the .xlsx | Not carried |
|---|---|
| Cell values - text, numbers, booleans, error values | Number formats: dates, currency and percentages arrive as plain numbers under General |
| Formulas, rewritten as formulas rather than frozen results | Fonts, fills, borders, alignment, conditional formatting |
| All sheets, with their names and order | Column widths, row heights, frozen panes |
| Merged cell ranges | VBA macros - .xlsx cannot hold them at all |
| Hyperlinks | Charts, images, pivot caches, slicers, form controls |
The number-format line is the one to plan for. A date is a number in Excel and the format that renders it is stored separately; the values cross and the formats do not, so a converted date column shows 45000 rather than 15/03/2023 until you select it and apply a Date format. Nothing has been lost, only its display rule.
Edge cases
- Pivot tables come through as their cached values, not as live pivots, because the pivot cache is not written. Rebuild the pivot from the converted data if you need it interactive.
- External links and data connections are not recreated. Formulas referring to another workbook keep their text but nothing re-establishes the connection.
- Password-protected workbooks cannot be read and fail with a conversion error rather than producing a partial file.
- Very large models are limited by the browser. There is no upload and no server, which is what keeps the file private and also what caps the practical size.
- Batch mode is one file in, one file out. Sheets are never merged across workbooks; use Excel Merge afterwards if you need that.
When converting is worth it
Convert when something other than Excel has to read the file. Google Sheets has no .xlsb importer; most Python and JavaScript spreadsheet libraries read .xlsx out of the box and need a separate package for .xlsb; and plenty of upload forms and ETL jobs validate on the extension alone. Keep the .xlsb when the workbook is a large live model you work in daily and Excel is the only thing that opens it - the speed and size advantages are real and the .xlsx copy loses the macros.
When to use a different tool
- You only need to read the file: XLSB Viewer opens it without producing a converted copy.
- You need the numbers rather than a workbook: Excel to CSV or Excel to JSON, both of which accept .xlsb directly.
- The source is an old Excel 97-2003 binary rather than .xlsb: XLS to XLSX.
- The converted file is too big: Compress Excel.
Frequently Asked Questions
XLSB is Excel's binary workbook format. It uses the same ZIP container as XLSX, but each worksheet is stored as a stream of binary records instead of XML. That makes it faster to open and save and usually smaller on workbooks with hundreds of thousands of rows or heavy formula chains, which is why finance and modelling teams switch to it. The cost is that only Excel really understands it.
No, and this catches people out because .xlsb is unusual: unlike .xlsx it can hold a VBA project without a separate macro-enabled extension. Converting to .xlsx therefore drops the macros - .xlsx is macro-free by definition. If the workbook runs code, keep the .xlsb, or open it in Excel and Save As .xlsm instead.
Yes. Formulas are read out of the binary records and written back into the .xlsx as formulas, so they still recalculate. Sheet names and order, merged cell ranges and error values come across too. Number formats do not: a date cell arrives as its serial number under the General format, so 15 March 2023 shows as 45000 until you apply a Date format to the column.
Often, yes - sometimes substantially. The binary records that make .xlsb compact become XML in .xlsx, and although both are ZIP archives, XML compresses less well than the records it replaces. A large model can grow by a factor of two or more. Compress Excel can claw some of that back by trimming unused range and dropping cached formula results.
Not one that this conversion introduces. XLSB and XLSX share the same ceilings - 1,048,576 rows and 16,384 columns per sheet - so nothing in a valid .xlsb can overflow the .xlsx. The real constraint is memory: the whole workbook is parsed and rewritten inside your browser tab, so a multi-hundred-megabyte model may be more than a laptop will manage.