XLSX vs CSV: What Is the Difference and When Should You Convert Excel to CSV?

XLSX and CSV can both represent rows and columns, but they are not simply “large” and “small” versions of the same spreadsheet format.

Quick answer

XLSX is an Excel workbook format that can store multiple worksheets, formulas, cell formatting and richer spreadsheet structures. CSV is essentially delimited text representing a flat table. Converting XLSX to CSV is useful for simple data exchange, but you should not expect formulas, charts, styling or multiple worksheets to survive as workbook features.

Does CSV preserve Excel formulas?

Normally not as an Excel workbook feature. CSV is intended to store text values in rows and columns. Workbook features such as formulas, charts, formatting and multiple sheets are not preserved in the same way.

Microsoft lists CSV as a comma-separated text format, separate from Excel workbook formats.

Can a CSV contain multiple worksheets?

A normal CSV represents one flat table. If an XLSX workbook has several sheets, conversion commonly requires selecting one sheet or exporting each sheet to a separate CSV.

ReFormatic explicitly notes that its XLSX-to-CSV workflow exports values from a selected worksheet and does not preserve formulas or formatting.

When should you use CSV?

CSV is often useful for:

• ecommerce product imports;
• moving data between software systems;
• scripts and databases;
• simple machine-readable feeds;
• workflows with a defined column schema.

When should you keep XLSX?

Keep XLSX when you need multiple worksheets, formulas, cell formatting, charts, pivots or continued editing as a spreadsheet workbook.

Why do CSV files sometimes break Vietnamese or other non-English characters?

CSV is text, so character encoding matters. If the importing application assumes the wrong encoding, accented characters can become corrupted. UTF-8 is common in modern workflows, but you should still check the target system's requirements.

Delimiter expectations can also vary by application and locale.

Convert XLSX to CSV with ReFormatic

1. Open ReFormatic Documents & Spreadsheets.
2. Select the XLSX file.
3. Choose the worksheet to export.
4. Choose CSV as the output.
5. Verify headers, non-English characters and a few sample rows before importing elsewhere.

Frequently asked questions

Is CSV smaller than XLSX?

It can be for simple data, but there is no universal rule because the formats store different kinds of structure.

Can converting CSV back to XLSX restore formulas?

No. If the CSV contains only exported values, the original formulas are no longer present to reconstruct.

Is CSV an Excel format?

Excel can open CSV files, but CSV is not an XLSX workbook. It is a text-based tabular data format.

Conclusion

Use XLSX when you need spreadsheet features. Use CSV when you need a simple, portable table for data exchange. Before converting, identify the worksheet you need and understand which workbook features will not survive the export.