Convert CSV to Excel (XLSX) online for free. Turn comma-separated data into a formatted spreadsheet. Fast, secure — no signup, no software.
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Checking files and selected output formats.
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CSV → XLSX is what you do when you've exported data from a database, analytics tool, or SaaS report as CSV but need Excel formulas, pivot tables, or charts on top. Preserves the raw data, adds an Excel-native structure. For very large CSV files (>1 M rows) Excel is not the right tool — Google Sheets caps at 10 M cells; better to query directly via BigQuery / Postgres.
XLSX is Excel's modern format — preserves formulas, formatting, multiple sheets, charts. Convert to XLSX when the recipient will interact with the data in Excel or Google Sheets (pivot tables, financial modelling, forecast workbooks). Overkill for one-off tabular data — CSV is lighter and more portable.
Technical comparison of the two formats — useful for deciding which to use, or for confirming what changes during conversion.
| Property | CSV | XLSX |
|---|---|---|
| Full name | Comma-Separated Values | Microsoft Excel (Open XML) |
| Year introduced | 1972 | 2007 |
| Developer / standard body | IBM (informal) | Microsoft |
| MIME type | text/csv | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| File extension | .csv | .xlsx |
| Compression | None | ZIP-compressed XML |
| Color / data depth | N/A | N/A |
| Max dimensions / size | Unlimited | 1,048,576 rows × 16,384 columns |
| Transparency | No | No |
| Animation | No | No |
| Standard / specification | IETF RFC 4180 | ECMA-376 / ISO/IEC 29500 |
| Best for | Data interchange, database imports, ETL pipelines | Modern Excel spreadsheets, data analysis |
CSV (Comma-Separated Values) is a plain text format that stores tabular data with each row on a new line and values separated by commas. CSV has no formal standard body, though RFC 4180 defines common conventions. Its simplicity makes CSV the most universally supported data interchange format — every spreadsheet, database, programming language, and analytics tool can read and write CSV files.
CSV files contain only raw data values with no formatting, formulas, charts, or metadata. This simplicity is both its strength and limitation: CSV files are compact, human-readable in any text editor, and import seamlessly into databases and data processing pipelines. CSV is the standard format for data exports, ETL workflows, machine learning datasets, CRM imports, and moving data between incompatible systems.
Quick answers about compatibility, quality, metadata handling, and the most common reasons to convert CSV files to XLSX.
