Convert CSV to an Excel file

Turn a CSV into a real .xlsx workbook. The header row is frozen and filtered, numbers are stored as numbers, and leading zeros and accents stay. Nothing is uploaded.

Paste CSV, drop a file, or try a sample

CSV, TSV, Excel, JSON, YAML, Markdown and HTML tables, and SQL inserts all work. Big files are fine.

Layout

The result shows here

Pick a format above. Copy it or download the file once your table is in.

Waiting for a table

    Your data stays on this device. Reading, converting and saving all happen in this browser tab.

    Keyboard shortcuts

    Open a file
    Ctrl O
    Copy the output
    Ctrl Enter
    Download the output
    Ctrl S
    Paste a file or text (outside the editor)
    Ctrl V
    Move around the table
    ↑ ↓ ← →
    Jump a screen
    Page Up Page Down
    First or last cell
    Ctrl Home End
    Column options (on a column name)
    Enter
    Copy the cell
    Ctrl C
    Search the source or output
    Ctrl F
    This list
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    To convert a CSV to Excel, drop the CSV above, check the table, and press Download .xlsx. You get a workbook where codes like 00412 stay text, numbers are real numbers, and the header row is bold, frozen and ready to filter.

    How do I convert a CSV to Excel?

    1. Drop the .csv or .tsv file on the converter, or paste the text.
    2. Check the Table tab. If everything sits in one column, set Delimiter to semicolon or tab.
    3. Rename or remove columns if you like, and give the sheet a name.
    4. Press Download .xlsx. To paste into a sheet you already have, press Copy for Excel instead and paste into a cell.

    Why not just open the CSV in Excel?

    When Excel opens a CSV directly, it guesses each column’s type. Microsoft’s own guide says that Excel removes leading zeros, shows large numbers in scientific notation (like 1.23E+15), and keeps only 15 significant digits (Microsoft Support, checked 4 November 2026). Excel can also misread UTF-8 accents in a CSV without a byte-order mark. A workbook built here sets each cell’s type from the whole column, so Excel does not have to guess.

    What’s in the workbook?

    • One sheet, named after your file unless you choose a name.
    • A bold header row that stays put as you scroll, with filter buttons on every column.
    • Column widths fitted to the data.
    • Whole numbers, decimals and true/false stored as values; YYYY-MM-DD dates as real dates. Numbers with more than 15 significant digits stay text, so they are not rounded.

    Converting many CSV files at once

    Choose several files in Open a file, or drop them together. The tool converts each CSV with the settings you chose, and the workbooks arrive in one ZIP.

    Going the other way

    Drop an .xlsx file here and pick CSV, JSON or another format to get the data back out. You choose which sheet to read, and formulas give their last calculated value. The CSV converter page covers every format.

    Questions

    Will Excel keep my leading zeros?

    Yes. The workbook stores values with a leading zero, such as ZIP codes or product codes like 00412, as text cells. Excel shows them exactly as they were.

    Are dates stored as real Excel dates?

    Columns where every value is a date in YYYY-MM-DD form become real Excel dates, formatted yyyy-mm-dd. You can sort and filter them by date. Other date styles stay text, because guessing whether 03/04 means March or April would be risky.

    Can I put several CSV files into one workbook?

    Not yet. Each CSV becomes its own workbook. Select or drop several CSV files at once to convert them all in one go. You get a ZIP with one .xlsx per file.

    What’s the biggest CSV I can turn into Excel?

    An Excel sheet holds up to 1,048,576 rows, so that is the limit. In our test, a 100,000-row CSV became a workbook in about two seconds. Larger tables take longer, but they show progress and you can cancel.

    Does the .xlsx work in Google Sheets, Numbers and LibreOffice?

    Yes. The workbook is a standard .xlsx file, which Google Sheets, Apple Numbers and LibreOffice Calc all open.

    Is my CSV uploaded?

    No. This browser tab builds the workbook and downloads it straight to your device. Nothing is sent to a server.

    Save what you find in one click.

    Kortex is a Chrome extension for Gemini Notebook (formerly NotebookLM). It sends AI chats, web pages, posts and YouTube videos into the notebook you pick. It keeps your notebooks organized. It exports them back out.

    Add to Chrome

    No card needed.

    Talk to the Kortex team

    This opens a pre-filled email in Gmail. We usually reply within a day.