Why Convert XLSX to CSV?
CSV (Comma-Separated Values) is the universal data interchange format. Every programming language, database, analytics tool, and data platform can read CSV files. When you need to import spreadsheet data into a SQL database, feed it to a Python script, load it into Google Sheets, upload it to a CRM, or send it to a system that does not speak Excel — CSV is the answer.
XLSX is Microsoft's proprietary spreadsheet format, an Open XML ZIP archive containing XML files for cell data, formatting, formulas, charts, pivot tables, and macros. While Excel is dominant in business environments, XLSX files cannot be directly consumed by most non-Microsoft tools without a dedicated parser library. CSV strips away all of Excel's rich features and leaves you with pure tabular data.
The conversion is simple in concept but has important nuances: formula handling, multi-sheet workbooks, encoding, date formats, and special character escaping can all trip you up if you are not aware of them.
What Gets Lost in XLSX-to-CSV Conversion
CSV is a flat text format. Converting from XLSX is inherently lossy for everything beyond raw cell values:
| XLSX Feature | Preserved in CSV? | Details |
|---|---|---|
| Cell values (text, numbers) | Yes | Core data preserved |
| Formulas | Values only | Formula results exported, not formulas |
| Formatting (bold, colors, borders) | No | All visual formatting lost |
| Multiple sheets | Partial | One CSV per sheet, or active sheet only |
| Charts and graphs | No | Completely lost |
| Merged cells | Partial | Value placed in first cell, others empty |
| Data validation (dropdowns) | No | Lost |
| Conditional formatting | No | Lost |
| Pivot tables | No | Lost (unless converted to flat data first) |
| Comments/notes | No | Lost |
| Images/embedded objects | No | Lost |
If you only need the raw data values, this is fine. If you need formatting preservation, consider converting to PDF instead.
Step-by-Step Conversion
Step 1: Prepare Your XLSX
Before converting, clean up the spreadsheet:
- Resolve all formulas. If formulas reference other sheets or external files, ensure those references are accessible. Broken references export as
#REF!or#VALUE!errors. - Flatten merged cells. Merged cells in CSV result in one cell with the value and adjacent empty cells. If this creates problems for your import, unmerge cells in Excel first.
- Remove or consolidate sheets. CSV supports one table per file. If your workbook has multiple sheets, you will either get one CSV per sheet or only the active sheet, depending on the converter.
- Check date formats. Excel stores dates as serial numbers (e.g., 45717 for 2025-02-24). The converter must format these correctly. Verify that dates appear as expected in the output.
Step 2: Choose Delimiter and Encoding
Delimiter — The character separating columns:
- Comma (,) — Standard CSV. Works everywhere. Can cause issues with data containing commas (e.g., addresses, descriptions).
- Semicolon (;) — Common in European locales where the comma is the decimal separator. Excel in European regions often defaults to this.
- Tab — Produces TSV (Tab-Separated Values). Avoids comma conflicts. Common for database imports.
- Pipe (|) — Rarely used in data content, so almost never causes delimiter conflicts.
Encoding — How text characters are stored:
- UTF-8 — The modern standard. Handles all languages and special characters. Use this unless you have a specific reason not to.
- UTF-8 with BOM — Adds a byte-order mark. Required by some older tools (including older Excel versions) to correctly interpret UTF-8.
- Latin-1 (ISO 8859-1) — Legacy Western European encoding. Only use if the consuming system requires it.
- Windows-1252 — Microsoft's extended Latin-1. Some legacy Windows applications expect this.
Step 3: Handle Multi-Sheet Workbooks
If your XLSX has multiple sheets, decide how to handle them:
- Active sheet only — Exports the currently selected sheet. Simplest option.
- All sheets to separate CSVs — Produces one CSV file per sheet, typically named
filename_Sheet1.csv,filename_Sheet2.csv, etc. - All sheets concatenated — Stacks all sheets vertically into one CSV. Only works if all sheets have the same column structure.
Step 4: Convert
Upload your XLSX to our XLSX to CSV converter and select your delimiter, encoding, and sheet handling preferences.
Quality and Settings Tips
Always verify the first few rows of output. Open the resulting CSV in a text editor (not Excel, which may reformat the data) and check that delimiters, encoding, and data values look correct. Common issues include date reformatting, number truncation, and escaped character problems.
Quoting rules matter. When a cell value contains the delimiter character (e.g., a comma in a comma-separated CSV), the value must be quoted: "123 Main St, Apt 4". When a cell value contains a quote character, it must be escaped as a double quote: "He said ""hello""". Most converters handle this automatically, but verify with a sample.
Large file handling. XLSX files can contain hundreds of thousands of rows. Converting a 500K-row spreadsheet to CSV is straightforward for the conversion itself, but consuming the output may require streaming or chunked reading in your application. A 500K-row XLSX might produce a 50-100 MB CSV.
Number precision. Excel stores numbers as IEEE 754 double-precision floating point. The conversion should preserve full precision (up to 15 significant digits). If you see unexpected rounding (e.g., 1.0000000000000002 appearing as 1), the converter may be truncating. Check settings for number formatting or precision options.
For the reverse direction — importing CSV data back into Excel format — see our CSV to XLSX converter.
Common Issues and Troubleshooting
Special characters appear garbled. This is an encoding mismatch. The CSV was saved in one encoding (e.g., UTF-8) but opened in a tool expecting another (e.g., Latin-1). Solution: explicitly specify UTF-8 encoding when importing the CSV. In Excel, use Data > Get Data > From Text/CSV and select UTF-8 encoding.
Dates show as numbers (e.g., 45717). The converter did not format Excel's serial date numbers into human-readable dates. Ensure date columns are recognized and formatted during conversion. In Excel, the date serial number 45717 equals 2025-02-24 (days since January 1, 1900).
Leading zeros are stripped from data (e.g., zip codes "00501" becomes "501"). CSV does not have a concept of text vs. number columns. When a consuming tool (especially Excel) opens the CSV, it may interpret numeric-looking text as numbers and strip leading zeros. Solutions: quote all values, or import into the consuming tool with explicit column types.
Formulas appear instead of values. Some converters export the formula text (=SUM(A1:A10)) rather than the computed value. Ensure the converter evaluates formulas before export. Alternatively, in Excel, copy the sheet, paste as values only, then convert.
Merged cell data is in unexpected positions. In CSV, merged cell content goes into the top-left cell of the merged range. All other cells in the merge appear empty. If your downstream tool expects data in every row, unmerge and fill down in Excel before converting.
Conclusion
XLSX-to-CSV conversion is a data-level operation — it preserves values and structure while discarding formatting, formulas, and rich features. Choose UTF-8 encoding for modern systems, verify delimiter handling with sample data, and pay attention to dates, numbers, and special characters. For multi-sheet workbooks, decide upfront whether you need separate CSVs or a single consolidated file.
Ready to convert? Try our free XLSX to CSV converter — no registration required.
