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CSV to XLSX Converter

Convert CSV files or pasted text to Excel XLSX in your browser. Auto-detect delimiter, preview, set sheet name, download.

About CSV to XLSX Converter

The CSV to XLSX Converter reads a CSV file or pasted text and produces an Excel-compatible XLSX file using the SheetJS library in your browser. The delimiter is auto-detected by counting comma, tab, semicolon, and pipe characters in the first 2000 characters, or you can override it manually. A custom RFC 4180-compliant parser handles quoted fields, escaped quotes, and Windows line endings. Set a sheet name, preview the first 50 rows in a table, and download the XLSX file — no server involved.

Why use CSV to XLSX Converter

  • Auto-detects delimiter so you don't need to know the format
  • Handles quoted fields, escaped quotes, and Windows/Unix line endings
  • Accepts both file upload and pasted text
  • Uses SheetJS for broad Excel compatibility — no server upload
  • Auto-detects delimiter so you don't need to know the format ahead of time
  • Handles quoted fields, escaped quotes, and Windows/Unix line endings out of the box

How to use CSV to XLSX Converter

  1. Upload a CSV file or paste CSV text directly into the textarea
  2. The delimiter is auto-detected, or choose one from the dropdown
  3. Optionally enter a custom sheet name for the Excel workbook
  4. Click 'Preview' to see the first 50 rows as a formatted table
  5. Click 'Download XLSX' to generate and save the Excel file
  6. The delimiter is auto-detected from the first 2000 characters, or choose one manually from the dropdown
  7. Optionally enter a custom sheet name for the Excel workbook (defaults to Sheet1)

When to use CSV to XLSX Converter

  • When a stakeholder needs data in Excel format but your export only offers CSV
  • When preparing a report for users who expect XLSX for formatting and filtering
  • When converting data from a database export (comma or tab-delimited) to Excel
  • When you need to name the worksheet something other than 'Sheet1'
  • When preparing a report for users who expect XLSX for filtering, formatting, and pivot tables
  • When converting a database export (comma or tab-delimited) to Excel for management review

Examples

Standard comma CSV

Input: Name,Age,City\nAlice,30,Boston\nBob,25,Chicago

Output: XLSX with Name, Age, City headers and two data rows; numeric Age column may render as integer in Excel

European semicolon CSV

Input: Produkt;Preis\nApfel;1,50\nBrot;2,99

Output: XLSX with Produkt and Preis columns; semicolon auto-detected; comma-decimal preserved as text

Quoted multi-line cells

Input: id,note\n1,"Line one\nLine two"\n2,"Simple"

Output: XLSX with two rows; row 1's note cell contains an internal newline (Alt+Enter style)

Tab-separated export

Input: Header1\tHeader2\tHeader3\nA\tB\tC

Output: XLSX with three columns and one row; tab auto-detected as delimiter

Tips

  • Paste a header row at the top of your CSV — SheetJS will treat it as the first row but Excel filtering works best when the header is row 1
  • If auto-detect picks the wrong delimiter, manually select the correct one and click Preview again
  • For CSVs from Excel (which often start with a UTF-8 BOM), the parser strips the BOM automatically before splitting
  • Use distinctive sheet names like 2024-Q3 or Customers-East so the workbook is self-documenting after download
  • For numeric columns with leading zeros (zip codes, phone numbers), wrap values in double quotes in the CSV — SheetJS keeps them as text
  • Test with a 50-row preview first; once satisfied, download the full XLSX in one click

Frequently Asked Questions

How does auto-detect work?▾
The tool counts comma, tab, semicolon, and pipe characters in the first 2000 characters and picks the most frequent one as the delimiter.
What CSV formats are supported?▾
Standard RFC 4180 CSV with optional quoting of fields containing the delimiter or newlines. Windows (CRLF) and Unix (LF) line endings are both supported.
Does it preserve numbers and dates as Excel types?▾
SheetJS may infer types from the cell content, but by default all values from the raw CSV string are treated as text unless they parse as numbers.
Is there a row or column limit?▾
The preview shows the first 50 rows. The XLSX itself will contain all rows. Very large CSVs (millions of rows) may be slow to process in the browser.
Can I paste multi-line cell content?▾
Yes. The CSV parser handles double-quoted fields containing newlines, so pasting data with wrapped cells works correctly.
What is the default sheet name?▾
Sheet1. You can change this in the Sheet Name field before downloading.

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CSV and TSV: The Universal Data Exchange Format Explained CSV files look trivial until you encounter a value with a comma inside it, a newline in a cell, or a file saved in the wrong encoding. This Mar 2026 · 7 min

Glossary

CSV
Comma-Separated Values — a plain-text tabular format where each line is a row and fields are separated by a delimiter, defined loosely by RFC 4180.
XLSX
Microsoft Excel's Open XML workbook format — a ZIP archive of XML files defining sheets, cells, shared strings, styles, and metadata.
Delimiter
The character separating fields in a CSV. Comma is the default, tab is used for TSV, semicolon is common in European Excel exports, and pipe is used in log files.
Quoted Field
A CSV field wrapped in double quotes to allow it to contain delimiters, newlines, or other quotes. Internal quotes are escaped by doubling them.
UTF-8 BOM
A three-byte byte-order mark (EF BB BF) prefixed to a UTF-8 file. The parser strips it automatically so it doesn't appear in the first cell.
Sheet Name
The label of a worksheet tab inside an Excel workbook. Maximum 31 characters; cannot contain : \ / ? * [ or ].
RFC 4180
The IETF document defining CSV grammar including quoting, escaping, and line endings. Most CSV-producing tools follow it loosely.
Frozen Rows
An Excel feature where the top N rows stay visible while scrolling. Not produced by this tool — apply manually in Excel after opening the XLSX.