Convert CSV to Excel
Formatted .xlsx
in one click.
Free CSV to Excel converter. Get a properly formatted .xlsx file — bold headers, auto-sized columns, frozen header row and type detection. No Excel installation needed. Runs entirely in your browser.
Three steps to a properly formatted .xlsx file — no Excel needed.
Drag your .csv file into the converter. A live preview table appears immediately — with styled headers and the first eight rows — so you can verify the data and column structure before converting.
Choose whether to apply bold header styling, auto-fit column widths, freeze the first row, and whether to detect numbers and dates automatically.
Click Convert and download the .xlsx file. It opens directly in Microsoft Excel, Google Sheets, LibreOffice Calc or Numbers — a proper Excel file, not a renamed CSV.
A CSV file is plain text — no formatting, no column widths, no data types. Every value is a string. When you open a CSV in Excel, it tries to guess types, sometimes incorrectly — long numbers become scientific notation, dates get misread, leading zeros disappear.
A .xlsx file is a structured binary format with explicit data types, cell formatting, column widths, sheet names and styling metadata. Numbers are stored as numbers, dates as date values — no guessing. CSVShift uses SheetJS to produce a proper .xlsx file with type coercion and full formatting.
Converting to Excel lets you build pivot tables, charts and conditional formatting directly in the file — without re-importing into a separate spreadsheet.
CSV files confuse non-technical colleagues. An .xlsx file ensures the recipient sees a properly formatted table with column headers they can sort and filter.
Converting to Excel with type detection ensures amounts are recognized as numbers — enabling SUM formulas, currency formatting and reconciliation calculations.
Converting the source CSV to Excel and copying it into a template saves time and eliminates transcription errors in business workflows.
| Option | Values | What it does |
|---|---|---|
| Sheet name | Any text (max 31 chars) | Sets the worksheet tab name. CSVShift pre-fills from your filename. |
| Header row style | Styled · Plain | Styled applies bold white text on navy background. Plain leaves the header unstyled. |
| Column widths | Auto-fit · Default | Auto-fit measures the longest value in each column (up to 100 rows). Default uses Excel's standard width. |
| Freeze header row | Freeze · No freeze | Freeze fixes row 1 so it stays visible when scrolling. Applied to the file — no manual step needed in Excel. |
| Value types | Auto-detect · Strings only | Auto-detect converts numeric strings to Excel numbers and dates. Strings only preserves leading zeros. |
Excel generated in
your browser. No upload.
CSVShift uses SheetJS — the most widely deployed open-source Excel library, used in thousands of production applications — to generate .xlsx files directly in your browser. Your CSV data is parsed locally and never transmitted to any server.