CSV to Excel Converter
Convert CSV to an Excel .xlsx file in your browser: real numbers, a bold frozen header row, auto-fit columns and a named sheet. Leading zeros stay intact, no upload.
How to use CSV to Excel
- 1Paste CSV or open a .csv, .tsv or .txt file and check the preview.
- 2Name the sheet and choose the bold header, freeze header and column width options.
- 3Click Download .xlsx to save the workbook.
What makes it better
- Writes a real .xlsx file, not a CSV renamed to .xls
- Numbers become Excel numbers; codes such as 007 and IDs of 16 or more digits stay text
- Bold header row, frozen top row and auto-fitted column widths
- Sheet name is cleaned to Excel's rules: 31 characters, none of [ ] : * ? / \
- Preview of the first 50 rows with a count of the rest
About CSV to Excel
CSV to Excel builds a genuine .xlsx workbook from pasted or opened CSV text, with numbers stored as numbers, an optional bold and frozen header row and columns sized to their content. You see a preview of the first 50 rows before you download, and the file is created on your device by the exceljs library.
Common uses
- Hand a CSV export to a manager who wants a formatted Excel sheet to filter and sort.
- Convert a bank or ERP download to .xlsx without Excel mangling postal codes or IDs.
- Create a workbook with a frozen header for a long list that will be scrolled a lot.
- Turn a semicolon-separated European export into a clean workbook.
Example
Input
Product,Qty,Price,Code Pen,12,1.5,007 Notebook,5,40,012 "Desk, small",1,2499.99,120
Result
Sheet1 · 4 rows × 4 columns · header bold and frozen · Qty and Price saved as numbers · Code kept as text (007, 012)
Good to know
- Dates stay as text by default because 03/04/2024 can mean two different days. Turn on Detect dates under Advanced to convert only unambiguous ISO dates such as 2024-03-01 into real Excel dates.
- A worksheet holds at most 1,048,576 rows and 16,384 columns. Anything beyond that is left out and the page tells you how many rows were cut.
- Text that starts with = is stored as plain text, not as a formula, so nothing in your CSV is calculated when you open the workbook.
CSV to Excel FAQ
How do I convert a CSV file to Excel?
Paste the CSV or open the file, check the preview, optionally rename the sheet, and click Download .xlsx. The workbook has one sheet containing every row.
Why do my leading zeros and long IDs survive?
Values such as 007 or a 16-digit account number are stored as text cells, because Excel would otherwise drop the zeros or round the digits above 15 significant figures.
Are numbers and dates converted?
Numbers are, so you can sum and sort them. Dates are only converted if you switch on Detect dates, and then only ISO forms like 2024-03-01 or 2024-03-01 14:30.
Is there a size limit?
The input limit is 20 MB, and Excel itself allows 1,048,576 rows per sheet. Large files are parsed in a background worker and rows beyond the Excel limit are reported and skipped.
Does the file leave my device when it is created?
No. The workbook is assembled in your browser tab with the exceljs library and saved straight to your downloads, so the CSV is never uploaded.