How to convert CSV to Excel
Drop the CSV, look at the preview to check the columns are right, and click Convert to Excel. The workbook is written as the file is read, so large files do not need to fit in memory. The header row becomes a bold first row.
The Excel row limit, and what this converter does about it
A sheet in Excel holds at most 1,048,576 rows and 16,384 columns. Opening a longer CSV in Excel silently drops everything past that limit. This converter never drops rows: when a file is longer, it writes the remainder onto Sheet2, Sheet3 and so on, repeating the header on each. A workbook that large will still be slow to open, so consider filtering or splitting the file first.
What is preserved
- Numbers become numeric cells, so they can be summed and sorted.
- Values with leading zeros, such as postcodes and IDs, stay text, so 00123 is not turned into 123.
- Numbers of more than 15 digits stay text, because Excel would round them.
- Dates stay as text exactly as they appear, so Excel does not reinterpret 03/04 as March or April for you.
- Cells over Excel’s 32,767-character limit are cut to that length and counted in the result.
Messy files, handled
- Quoted fields that contain commas, doubled quotes and line breaks are read correctly, so a note with a newline in it does not split into two rows.
- Comma, semicolon, tab and pipe delimiters are detected from the start of the file, including the semicolons European exports use.
- A byte-order mark, and Windows (CRLF) or Unix (LF) line endings, are handled.
- Rows with more or fewer fields than the header are counted and shown, not silently dropped.
- Files with no header row are supported with one checkbox.
- UTF-8 files are supported. A UTF-16 file needs saving as UTF-8 first, and the tool tells you so.
How to use it
- Drop the CSV file onto the box.
- Check the preview and the row count.
- Click Convert to Excel (.xlsx).
- Download the workbook.
Frequently asked questions
Can I convert a CSV with more than a million rows to Excel?
Yes. The rows past 1,048,576 are written to additional sheets in the same workbook. Excel will be slow with a workbook that large, so filtering or splitting first is often better.
Will leading zeros be kept?
Yes. Values like 00123 are written as text, not numbers, so they are not changed.
Why not just open the CSV in Excel?
Excel drops rows beyond its limit, converts values it thinks are dates or numbers, and can mangle long numbers and leading zeros. Converting first gives you the data as it is in the file.
How large a CSV file can it handle?
The largest file it has been run on is 1 GB, opened and scrolled in a real browser. It streams the file instead of loading it, so memory grows with the number of rows (about 8 bytes each for the index), not with the size of the file. Very large row counts, roughly above a hundred million, may exhaust a browser tab’s memory.
Is my file uploaded anywhere?
No. The file is read in pieces by code running in your browser and is never sent to a server. The site records only an anonymous counter with the operation and rough size buckets, such as “100–500 MB” and “1M–10M rows” — never file names, column names or any data.