XLSX to CSV Converter
Convert an Excel workbook to CSV without uploading it.
File
Result
Your converted file will appear here.
About the XLSX to CSV converter
Spreadsheets are where confidential data lives — payroll, customer lists, financials — which makes uploading one to a conversion site an odd thing to do routinely. This converter reads the workbook in your browser.
An .xlsx file is a ZIP archive of XML, and browsers can now decompress and parse both natively, so this needs no library and no server.
Choosing a sheet
By default the first sheet containing any data is used, which skips the empty cover sheets workbooks often start with. You can name a sheet exactly, or give its position as a number.
If the name does not match, the error lists every sheet in the workbook so you can see what is actually there.
Dates, and why they arrive as numbers
Excel stores a date as the number of days since 1900 and remembers only the display format. Read naively, 31 January 2024 comes out as 45322.
With date conversion on, cells formatted as dates are written as ISO dates instead. Turn it off if you want the raw serial numbers — occasionally you do, for arithmetic.
What is not carried over
CSV holds values and nothing else, so formatting, formulas, merged cells, charts and multiple sheets are all lost. Formula cells export their last calculated value, which is what Excel had stored.
Frequently asked questions
Does this work with old .xls files?
No. The legacy .xls format is a completely different binary layout. Open it in Excel or LibreOffice and save as .xlsx first.
Can I convert every sheet at once?
Not in one pass — CSV holds a single table. Run the converter once per sheet.
What about password-protected workbooks?
They cannot be opened. Remove the protection in Excel first.
Is my data uploaded?
No. The conversion runs in your browser, which matters here — configuration files and spreadsheets routinely contain credentials and personal data.