Excel to CSV Converter
Excel to CSV Converter transforms XLSX files into RFC 4180 compliant CSV format entirely within your browser. The tool uses client-side processing, ensuring your data never leaves your device.
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Max file size: 100 MB · Max 10 files at once
The Excel to CSV Converter converts Excel spreadsheets (.xlsx) to CSV files with high accuracy, handling merged cells, date serials, and formula results. Utilizing the SheetJS (xlsx library v0.18) entirely in-browser, it processes files up to 100MB without uploading data to any server, preserving privacy. This client-side approach ensures fast conversions and data security. For further data manipulation, explore related tools like CSV to XLSX for reverse conversion or XLSX to JSON to export spreadsheets as JSON.
How to Use Excel to CSV Converter
- Click the upload button and select your
.xlsxfile (recommended max size 100MB). - The tool reads the binary data using SheetJS's
read()function withtype:'array'. - It extracts the first worksheet (SheetNames[0]) and processes merged cells by unmerging them.
- Date serial numbers in Excel are converted to ISO 8601 date strings for CSV compatibility.
- Finally, the worksheet data is converted to RFC 4180 compliant CSV using
utils.sheet_to_csv()and downloaded as a.csvfile.
How It Works
This tool leverages the SheetJS (xlsx) library version 0.18, operating fully on the client side within your browser. It reads the XLSX file's binary content as an array buffer, ensuring efficient memory usage. The first worksheet is selected because CSV format supports a single sheet, so multi-sheet workbooks export only the initial sheet data.
Merged cells are handled by unmerging, duplicating cell values across merged ranges to maintain data integrity. Excel stores dates as serial numbers; these are converted to ISO 8601 strings (e.g., 2024-06-01) to preserve temporal data accurately in CSV. Formula results are extracted using cached values to avoid recalculation or errors.
The output CSV is compliant with RFC 4180, using commas as delimiters and double quotes for strings containing commas or line breaks. Running entirely in-browser means no data is transmitted to servers, enhancing privacy and security. However, browser memory limits recommend files stay under 100MB for smooth processing.
Example
Input Excel (Sheet1):
| Name | Date | Sales |
|-------|------------|---------|
| Alice | 44927 | =B2*100 |
| Bob | 44928 | 300 |
Output CSV:
"Name","Date","Sales"
"Alice","2023-01-01","4492700"
"Bob","2023-01-02","300"
When to Use Excel to CSV Converter
- Developers needing to convert Excel files into CSV for data import in applications or databases.
- Designers preparing CSV data for visualization tools that require flat file formats.
- SEO specialists extracting keyword lists or metadata stored in Excel to CSV for analysis.
- Students or researchers exporting spreadsheet data into CSV for statistical software or programming projects.
- Anyone requiring a quick, private conversion without uploading sensitive Excel data to external servers.
For alternate conversions, use CSV to XLSX to convert CSV back to Excel or XLSX to JSON to export Excel data as JSON.
Frequently Asked Questions
Does the Excel to CSV Converter support multiple worksheets?
No, this tool extracts only the first worksheet (SheetNames[0]) from the XLSX file for conversion. CSV format inherently supports single-sheet data, so multi-sheet workbooks must be processed sheet-by-sheet.
How does the tool handle Excel date formats during conversion?
Excel stores dates as serial numbers. The converter transforms these serials into ISO 8601 date strings (YYYY-MM-DD) in the CSV output, ensuring dates remain accurate and parseable in downstream applications.
Are formulas preserved in the CSV output?
Formulas themselves are not preserved; instead, the converter uses cached formula results stored in the XLSX file. This means the CSV contains the computed values, not the formula expressions.
Is my data uploaded to a server during conversion?
No. All processing occurs entirely within your browser using the SheetJS library. Your Excel data never leaves your device, providing strong privacy and security guarantees.
What is the maximum file size supported by this converter?
The recommended maximum file size is 100MB due to browser memory constraints. Larger files may cause performance issues or failure during processing.
How does the converter handle merged cells in Excel?
Merged cells are unmerged during conversion, with the content duplicated across the merged range in the CSV output. This preserves data visibility and structure without losing information.