CSV to XLSX Converter
Convert CSV files to Excel XLSX online for free. Preserves columns, rows, and data types. Opens in Microsoft Excel, Google Sheets, or LibreOffice. Up to 100 MB.
Drop your CSV file hereTap to choose your CSV file
or
Supports .csv, .tsv • Max 100 MB
How to Convert CSV to XLSX
Upload
Drag and drop your CSV file into the converter above, or click Choose CSV File to browse your device.
Convert
Click Convert to XLSX. Our server parses your CSV data and builds a proper Excel spreadsheet with columns, rows, and data types.
Download
Click Download XLSX to save the Excel file. That's it — no registration, no email required.
What is CSV?
CSV (Comma-Separated Values) is a plain text format for storing tabular data. Each line represents a row, and values within a row are separated by commas. The format has existed since the early days of computing and is supported by virtually every application that handles data.
CSV is lightweight and human-readable, but it has significant limitations: no data typing (everything is text), no formatting, no formulas, no multiple sheets, and no standard for encoding or delimiters across locales.
What is XLSX?
XLSX is Microsoft Excel's modern spreadsheet format, introduced with Office 2007. It stores data in XML files inside a ZIP archive, supporting multiple worksheets, cell formatting, formulas, charts, pivot tables, and data validation.
Unlike CSV, XLSX preserves data types — numbers stay as numbers, dates are recognized as dates, and text with leading zeros is not silently truncated. XLSX files open in Microsoft Excel, Google Sheets, LibreOffice Calc, and Apple Numbers.
CSV vs XLSX: Quick Comparison
| Feature | CSV | XLSX |
|---|---|---|
| Format type | Plain text | XML in ZIP archive |
| Data types | Everything is text | Numbers, dates, booleans, text |
| Multiple sheets | No (single table) | Yes (unlimited worksheets) |
| Formulas | Not supported | Full formula engine |
| Formatting | None | Fonts, colors, borders, styles |
| File size | Very small | Larger (but compressed) |
| Human-readable | Yes (open in text editor) | No (binary archive) |
| Max rows | Unlimited | 1,048,576 per sheet |
| Leading zeros | Preserved in file, lost on import | Preserved with text formatting |
| Best for | Data exchange, scripts, APIs | Analysis, reporting, sharing |
When to Use XLSX Over CSV
Preserve Data Types and Formatting
CSV treats everything as plain text. When you open a CSV in Excel, phone numbers like 00447911123456 lose their leading zeros, dates like 01/02/2025 may be misinterpreted, and large numbers get converted to scientific notation. Converting to XLSX before sharing ensures recipients see the data exactly as intended.
Add Formulas and Charts
CSV cannot store formulas, charts, or conditional formatting. If you need to add SUM, VLOOKUP, pivot tables, or data visualizations to your data, you need XLSX. Converting your CSV to Excel first gives you the full power of spreadsheet analysis.
Share Professional Reports
Sending a CSV file to clients or stakeholders looks unprofessional — it opens as a wall of unformatted text. XLSX supports headers with bold fonts, color-coded rows, column widths, and sheet names. Converting to Excel lets you present data in a polished, business-ready format.
Work with Multiple Datasets
Each CSV file contains a single flat table. If your data has multiple related tables (e.g., orders + customers + products), you need separate CSV files. XLSX supports multiple worksheets in a single file, keeping related datasets organized and easy to cross-reference with formulas.
Practical Scenarios: XLSX Instead of CSV
Financial and Accounting Data
Financial records demand precision. CSV files silently drop leading zeros from account numbers, truncate long IBANs, and convert currency values to ambiguous text strings. XLSX preserves number formatting, supports dedicated currency and accounting cell formats, and lets you apply formulas like SUMIF or VLOOKUP across worksheets. If you export transaction logs, invoices, or budget reports from your accounting software as CSV, converting to XLSX before distribution prevents rounding errors and ensures decimal precision.
Inventory and Product Catalogs
E-commerce platforms and ERPs often export product data as CSV. The problem: SKUs with leading zeros (like 007842) become 7842, EAN-13 barcodes get converted to scientific notation, and price columns lose their decimal places. Converting to XLSX locks in text formatting for identifiers and number formatting for prices. You can also use data validation in XLSX to restrict category columns to a predefined list, reducing manual entry errors when the file is edited by warehouse staff.
Survey Results and Research Data
Research datasets exported from tools like Google Forms, Typeform, or Qualtrics arrive as CSV. Once converted to XLSX, you can freeze header rows, apply conditional formatting to highlight outliers, create pivot tables for cross-tabulation, and add charts directly in the workbook. XLSX also supports cell comments, which are useful for annotating anomalies or flagging responses that need review during data cleaning.
HR and Employee Records
Payroll exports, attendance logs, and employee directories contain sensitive structured data. CSV provides no way to protect sheets, hide salary columns, or lock cells from editing. XLSX supports sheet protection, hidden columns, and named ranges that make formulas easier to audit. Converting to XLSX before sharing with department heads allows you to control exactly which data is visible and editable, while keeping the full dataset intact in a protected sheet.
Common CSV Encoding Issues
CSV is deceptively simple. Under the surface, there are several encoding and parsing pitfalls that corrupt data silently when files move between systems, locales, or applications.
UTF-8 BOM (Byte Order Mark)
Many applications — including older versions of Excel — expect a UTF-8 BOM (the three-byte sequence EF BB BF) at the start of a CSV file to correctly display non-ASCII characters like accented letters, Cyrillic, or CJK text. Without it, characters appear garbled (e.g., Müller instead of Müller). Conversely, some programming tools treat the BOM as data and inject invisible characters into the first column header. Converting to XLSX sidesteps this entirely: XLSX uses XML with explicit encoding declarations, so characters are always interpreted correctly regardless of the source system.
Delimiter Detection and Locale Conflicts
The "comma" in CSV is not universal. In countries that use the comma as a decimal separator (Germany, France, Brazil, and much of Europe), CSV exports use semicolons as field delimiters instead. When a German-locale CSV file is opened on an English-locale machine, Excel splits columns incorrectly because it expects commas. Tab-separated files (.tsv) avoid this but introduce their own issues with fields that contain literal tabs. Our converter auto-detects the delimiter by analyzing the first several rows of your file, then maps each field to the correct XLSX cell — eliminating delimiter ambiguity.
Date Format Misinterpretation
Dates are the most commonly corrupted data type in CSV files. The value 01/02/2025 means January 2 in the US (MM/DD/YYYY) but February 1 in Europe (DD/MM/YYYY). Excel interprets dates based on the system locale, not the file's origin. Worse, ambiguous dates like 03/04/2025 are silently reinterpreted with no warning. ISO 8601 format (2025-01-02) avoids this, but most real-world exports do not use it. When you convert CSV to XLSX through our tool, date columns are parsed and stored as proper Excel date serial numbers with explicit formatting, so the value is unambiguous regardless of which locale opens the file.