Turn a plain CSV file into a proper .xlsx workbook you can open and format in Excel. Converts in your browser — nothing uploaded. Free.
🔒 Runs entirely in your browser — your data never leaves your device.
CSV is universal but bare — no formatting, no formulas, and awkward quirks when you double-click it (leading zeros vanish, long numbers become scientific notation, dates reinterpret themselves). Converting to a real .xlsx gives you a proper spreadsheet to format, chart and calculate in, and this conversion is perfect-fidelity because both formats simply hold rows and columns of data. Exports from your bank, POS, or analytics that arrive as CSV become workbooks in one click.
Need to go the other way? Excel to CSV. Want a PDF of the data instead? Excel to PDF. For quick data reshaping, the CSV to JSON tool helps developers.
A CSV to Excel converter reads a plain-text CSV (comma-separated values) file and rebuilds it as a genuine .xlsx workbook — the format Excel, Google Sheets, and most spreadsheet apps actually prefer. A CSV holds the same underlying data, rows and columns of values, but with none of the formatting, formulas, or type-handling a real spreadsheet file has. That gap is exactly what causes the classic CSV headaches: double-click a CSV straight into Excel and leading zeros on postcodes or ID numbers silently vanish, long account numbers flip into scientific notation, and date-like text reinterprets itself using your system's locale settings.
Converting to .xlsx first — rather than opening the raw CSV directly — sidesteps most of that. Your values land in cells as written, and you can format cautious columns (postcodes, phone numbers, reference codes) as Text afterward to lock them from being reinterpreted.
| CSV | Excel (.xlsx) | |
|---|---|---|
| Formatting, colours, fonts | None | Fully supported |
| Formulas | None — values only | Fully supported |
| Leading zeros / long numbers | Often altered when opened directly | Preserved as entered |
| Opens in | Any text editor or spreadsheet app | Excel, Sheets, LibreOffice, Numbers |
| Who | Common Use |
|---|---|
| 💼 Business & accounts | Turn a bank, POS, or payment gateway CSV export into a real spreadsheet to analyse |
| 📊 Analysts & marketers | Convert analytics or CRM data exports into Excel for pivot tables and charts |
| 🧑💻 Developers | Turn a database or API CSV export into a shareable spreadsheet for non-technical teammates |
| 🎓 Students & researchers | Convert raw survey or dataset CSVs into a formatted workbook for analysis |
| 📱 Anyone | Open a stubborn CSV correctly, without Excel silently mangling IDs or dates on double-click |
Is my data uploaded?
No — the CSV is read and rewritten as .xlsx inside your browser. Nothing is sent to a server, so it's safe for financial and personal data.
Does it fix the "leading zeros disappearing" problem?
Converting to .xlsx preserves your cell values as written far better than double-clicking a CSV. For fields like postcodes or IDs, format the column as Text in Excel afterwards to lock them.
Will it handle commas inside fields?
Yes — properly quoted CSV fields containing commas are parsed correctly and land in a single cell.
What about semicolon-separated files?
Standard comma CSVs work best. If your file uses semicolons (common in some regions), the parser handles common delimiters, but comma-separated is the most reliable input.
Can I open the result in Google Sheets?
Yes — the .xlsx opens in Excel, Google Sheets, LibreOffice, and Numbers.
What's the difference between opening a CSV in Excel and converting it here?
Double-clicking a CSV lets Excel auto-guess formatting as it opens — which is exactly what strips leading zeros and reinterprets dates. Converting to .xlsx first preserves your values as written, so you control the formatting afterward instead of Excel guessing for you.
Does this convert plain text (.txt) files too?
This tool is built for .csv files. If your data is comma-separated but saved with a .txt extension, rename the file extension to .csv first, then upload it here.
Can I convert multiple CSV files at once?
Not currently — it converts one file at a time. Repeat the same steps for each additional CSV you need to convert.