CSV to Excel Converter
Turn pasted CSV into a real .xlsx workbook with SheetJS. Cells are written as text, so Excel can't strip leading zeros or turn codes into dates when the file opens.
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Excel to CSV Converter
Pull the first sheet of an Excel workbook out to plain CSV in your browser. Formulas become their values, and the file stays on your computer.
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Quick answer
Drop an Excel file (.xlsx or .xls) and this extracts its first sheet to plain CSV using the SheetJS library, right in your browser. Formulas are written out as their computed values. Styling, colours and merged cells fall away because CSV holds plain text only. The file is read on your device and never uploaded.
What the Excel to CSV Converter does
Drag in (or pick) an .xlsx or .xls workbook and the tool converts its first sheet to comma-separated values, ready to copy or download. The conversion is instant and happens on your machine.
Databases, scripts, BI tools and most other apps read CSV even when they can't open a native .xlsx, so this is a quick way to move spreadsheet data into the next system.
How it works
SheetJS reads the workbook (a zipped Office Open XML bundle, or a legacy .xls) in the browser, takes the first sheet, and serialises its cells to comma-separated values, quoting any field that needs it under RFC 4180.
Only the first sheet is converted. Formula cells come out as their last-calculated results. Fonts, fills, column widths and merged cells are dropped, because CSV stores values and nothing else.
Data source & conversion logic
No external data. SheetJS parses the Office Open XML (or legacy .xls) workbook in your browser and writes RFC 4180 CSV.
- Step 1. Read the dropped workbook with SheetJS (Office Open XML or .xls).
- Step 2. Select the first sheet.
- Step 3. Convert its cells to CSV, quoting fields that need it per RFC 4180.
- Step 4. Write formula cells as their computed values.
- Step 5. Copy the CSV or download it.
Privacy
The workbook is read in your browser by SheetJS and never uploaded.
The data lives only in the open page and is gone when you close it.
You can use it on confidential spreadsheets such as budgets or HR data.
Technical details
| Input | .xlsx or .xls (drag-and-drop) |
|---|---|
| Output | CSV, first sheet only |
| Engine | SheetJS |
| Formulas | Written as their computed values |
| Formatting | Dropped (values only) |
| Encoding | UTF-8 text |
| Where it runs | In your browser; the workbook is not uploaded |
Standards and references
- Office Open XML / .xls (ECMA-376, ISO/IEC 29500): the workbook formats SheetJS reads: the modern zipped-XML .xlsx and the legacy binary .xls.
- RFC 4180: sets the CSV output rules: a comma delimiter, with quotes around fields that contain commas, quotes or line breaks.
- SheetJS: the in-browser library that parses the workbook.
Accuracy and limits
A multi-tab workbook converts just its first sheet. For the others, use the Excel sheet splitter.
Formulas become values. The CSV captures what each formula evaluated to, not the formula itself.
Formatting is lost by design: colours, fonts, number formats, merged cells and column widths have no equivalent in CSV.
If you reopen the CSV by double-clicking it in Excel, Excel may re-type the values, stripping leading zeros or turning codes into dates. Import through Data → From Text/CSV as Text to avoid that. The re-typing comes from Excel, not from this tool.
Real-world uses
Import into a database or script
Get spreadsheet data into a system that reads CSV but not .xlsx.
Feed a data pipeline
Hand a BI or ETL tool the CSV it expects.
Share one sheet lightly
Send a single sheet as a small, universal text file.
Strip down a workbook
Reduce a styled .xlsx to just its values for processing.
When it fits, and when it doesn't
Good for
- Extracting the first sheet to CSV
- Universal import into other systems
- A lightweight text export
- Stripping an .xlsx to plain values
Not the best choice for
- Multi-sheet workbooks
- Keeping formulas, types or formatting
- Very large sheets in a low-memory browser
Need every sheet? Use the Excel sheet splitter. Need to keep formulas, types and formatting? Keep it as .xlsx. Re-importing into Excel? Use Data → From Text/CSV and set the columns to Text.
Frequently asked questions
Which sheet gets converted?
How do I convert the other sheets?
What happens to formulas?
Is formatting kept?
Is my file uploaded?
Does it read old .xls files too?
Why might Excel mangle the CSV when I reopen it?
How do I keep leading zeros when reopening in Excel?
What about very large workbooks?
Does it handle commas inside cells?
References
Checked against the SheetJS conversion this page runs: first sheet only, formula results instead of formulas, and the whole job done in your browser.
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Back to the Excel to CSV Converter
Paste or pick your input at the top of the page. The conversion runs on this device and needs no account.