Why convert CSV to XLSX?
- To share with a non-technical colleague. XLSX opens with one double-click; CSV opens in a text editor unless your machine is set up for it.
- To preserve text columns. Excel mangles long numeric IDs (ZIP codes, phone numbers) when you import a CSV — opening a real XLSX avoids the auto-typing.
- To build on. Add formatting, charts, or formulas on top of clean data without re-importing every time.
- To email. Many corporate inbound-mail filters block .csv attachments as "suspicious" but pass .xlsx through.
What's handled
- Delimiter detection. The converter sniffs the first 4 KB of the file for commas, semicolons, tabs, or pipes. European exports (semicolon-delimited because the comma is their decimal separator) and tab-separated TSV files are handled the same way.
- UTF-8 with BOM. Excel-on-Windows exports CSV as UTF-8 with a leading byte-order mark. The converter strips the BOM transparently so the first column isn't named "
name". - Quoted fields. RFC 4180-style quoting:
"hello, world"stays a single cell, embedded newlines inside quoted fields are preserved, doubled quotes ("") read as a literal quote. - Cell typing. Every cell is written as a string. When you open the XLSX, Excel applies its own type detection on display — dates and numbers usually render as you'd expect, leading zeros and long IDs stay safe as text.
How it works
- Use the converter above. No signup required.
- Drop your CSV files. Drag and drop one or more CSV files into the upload box (up to five files, 20 MB each). Comma, semicolon, tab, and pipe delimiters are all detected automatically.
- Choose XLSX as the output. Pick XLSX from the dropdown; quoted fields stay as single cells, UTF-8 BOM is handled transparently.
- Convert and download. Click Convert; a download link appears as each file finishes. The result opens in Excel, LibreOffice Calc, Google Sheets, and Apple Numbers.
Good for
- Handing a script's CSV output to a colleague who works in Excel.
- Email attachments that need to make it through corporate spam filters.
- Re-importing CSV exports without losing leading-zero columns to Excel's auto-typing.
- Starting an analysis in Excel from a clean tabular dataset.
FAQ
What delimiters does the converter detect? We sniff for commas, semicolons, tabs, and pipes from the first 4 KB of the file. Most files come back as standard comma-separated. European exports (semicolon-delimited because the comma is their decimal separator) and tab-separated TSV files are handled the same way.
Will my dates and numbers be typed correctly in the XLSX? Every cell is written as a string. Excel's own type-detection kicks in when you open the file — it'll turn 2026-05-23 into a date and 1500 into a number on its own. Leading zeros and very long numeric IDs (ZIP codes, phone numbers) stay safe as text. If you need explicit number/date typing on write, convert to XLSX in Excel directly.
Does it handle quoted fields with commas or newlines inside? Yes. The CSV reader is RFC 4180-compliant: a value like "hello, world" stays in a single cell, and a quoted field containing a newline also stays one cell. Doubled quotes inside a quoted field ("") are read as a single literal quote.
Can I open the result in Google Sheets and Numbers? Yes. The output is a standard .xlsx (Office Open XML) file. It opens in Excel 2007 and later, LibreOffice Calc, Google Sheets, Apple Numbers, and every other spreadsheet tool that reads XLSX — no compatibility flags or special export needed.
Is the CSV to XLSX conversion free? Yes. No signup, no watermark, no time-limited trial. Free for personal and commercial use, up to five CSV files per upload at 20 MB each.
Related
- XLSX → CSV → the reverse trip, into a pipe-friendly text file
- CSV → PDF → a printable table when you don't need editability
- XLSX → PDF → finalize a styled spreadsheet
- DOCX → PDF → the document-family equivalent
- CSV → JSON → turn rows into structured JSON