How to use the CSV to Excel Without Losing Leading Zeros
- Choose a CSV or TSV file, or paste the data.
- Check the delimiter, then select Convert to Excel.
- Review the preview and download the XLSX file.
Supported files and limits
- Every value is stored as text, so customer numbers, IBANs, phone numbers and invoice IDs stay exactly as written. Excel will not calculate with them until you convert a column yourself.
- Formulas in the CSV are kept as plain text and never run.
- One worksheet, up to 5,000 data rows, 100 columns and 10 MB. Every row must have the same number of columns as the header.
- The file must be UTF-8 encoded.
Common questions
Why does Excel remove leading zeros from my CSV?
A CSV file has no column types, so Excel guesses. Values that look like numbers are converted, which drops leading zeros and replaces every digit after the fifteenth with a zero.
How is this different from opening the CSV in Excel?
The XLSX file created here marks every cell as text, so Excel opens it without guessing and nothing is changed.
Can I still calculate with number columns?
Yes. In Excel, select the column and use Data > Text to Columns, or a formula such as VALUE(), to convert just the columns you need.
Is my file uploaded?
No. The conversion runs in your browser, and your data is never sent to our server or anyone else.