How to use it
- Drop your .csv, .tsv or .txt file here.
- Check the preview; adjust delimiter, encoding or number format if needed.
- Choose whether the first row is a header.
- Click Convert to Excel (.xlsx).
Why not just open the CSV in Excel?
Double-clicking a CSV often goes wrong in ways that are easy to miss:
- Leading zeros disappear. ZIP codes like 02134 become 2134, and product codes lose their zeros.
- Long numbers get mangled. Credit card-style IDs, tracking numbers and account numbers over 15 digits turn into scientific notation and lose digits, because Excel stores numbers with 15 significant digits.
- Everything lands in column A when the file uses semicolons or tabs instead of commas.
- Accented characters turn into gibberish (José instead of José) when the encoding is guessed wrong.
- Numbers stay as text or dates and decimals are misread when the file came from a system with a different number format.
This converter handles those cases before Excel ever sees the data, and gives you a real .xlsx file.
What the converter does
| Step | Detail |
|---|---|
| Delimiter | Detected automatically: comma, semicolon, tab or pipe. You can override it. |
| Encoding | UTF-8 is detected; other files are read as Windows-1252, the usual encoding of CSVs saved by older US versions of Excel. Windows-1250 and ISO-8859-2 are also available. |
| Numbers | Decimal point (1,234.56) or decimal comma (1.234,56) is detected from the data, or you choose. You can also keep everything as text. |
| Header row | Optional: bold, frozen at the top, with filter buttons |
| Leading zeros and long numbers | Kept as text so they do not change |
The preview shows the first 8 rows and 12 columns, plus the detected settings, so you can check before converting. All rows and columns go into the Excel file.
Private: data stays in your browser
CSV exports often contain customer lists, transactions or payroll data. The conversion runs in your browser, so the file is never uploaded. CSV files up to 50 MB are supported; for bigger files, split them first or use Excel's own import wizard.
The workbook is a standard .xlsx file, so it opens in Excel for Windows and Mac, Google Sheets, Apple Numbers and LibreOffice Calc. Quoted fields with commas or line breaks inside them are handled correctly, so an address like "123 Main St, Apt 4" stays in one cell.
A worked example
Your online store exports orders as orders.csv. Opened directly, the ZIP code column shows 2134 instead of 02134, order IDs like 1234567890123456789 appear as 1.23457E+18, and customer names with accents look garbled. Drop the file here: the preview shows comma-delimited data, UTF-8 encoding and decimal-point numbers. Leave First row is a header on and click Convert to Excel. In orders.xlsx the ZIP codes keep their zeros, the order IDs are intact as text, prices are real numbers you can sum, and the header row is bold with filters ready to use.
Tips
- Wrong columns in the preview? Pick the delimiter manually.
- Odd characters? Try another encoding; the preview updates instantly.
- Numbers off by a factor of 1,000? The file probably uses a different decimal separator; switch the Numbers setting.
- Need to keep everything exactly as typed? Choose Keep everything as text.
- Sheet names are limited to 31 characters, so long file names are shortened for the sheet tab.
Frequently asked questions
How do I convert CSV to Excel without losing leading zeros?
Use this converter. Values with leading zeros, such as ZIP codes, are stored as text in the XLSX file so the zeros stay.
Which delimiters are supported?
Comma, semicolon, tab and pipe. The delimiter is detected automatically, and you can change it.
Why do accented letters look wrong?
The file's encoding was guessed incorrectly. Choose a different encoding in the settings and check the preview.
Is there a file size limit?
Files up to 50 MB can be converted in the browser.
Is my data uploaded?
No. The CSV is converted in your browser and never leaves your device.
Last updated: November 12, 2026