How to use CSV to Excel
- 1Drop one or more CSV, TSV or TXT files into the box.
- 2Check the detected encoding and delimiter next to each file, and change them if the preview looks wrong.
- 3Set the options: header row, convert numbers, keep dates as text and filter buttons.
- 4In the preview, click Auto under any column name to keep that whole column as text.
- 5Click Convert to Excel. Several files become one workbook with one sheet per file.
What goes wrong when you double-click a CSV
When Excel opens a CSV file directly it guesses the type of every value. ZIP code 02134 becomes 2134, a phone number like 01012345678 loses its first zero, a 16-digit card or order number is rounded to 1.23457E+15, and part numbers like 1-2 can turn into dates. If the file was saved in a different encoding, accented or Korean text becomes unreadable.
This converter decides the type of each value itself and writes it into the XLSX file directly, so Excel has nothing left to guess:
- Values with a leading zero, a leading + sign or more than 15 digits are always stored as text.
- Ordinary numbers, numbers with thousands separators (1,500,000) and percentages (12.5%) become real numbers you can sum, with their format kept.
- Dates written as 2024-01-15, 2024/1/15 or 2024.1.15 become real Excel dates, or stay as text if you turn on Keep dates as text. Ambiguous dates like 03/04/2024 are left as text.
- Any column can be locked to text with one click in the preview.
Encoding and delimiter detection
The tool reads the raw bytes and recognizes UTF-8, UTF-8 with BOM, UTF-16, Korean EUC-KR/CP949 (the default for CSV saved by Korean Excel), Japanese Shift_JIS and Western Windows-1252. It also detects whether values are separated by commas, semicolons (common in Europe), tabs or pipes. Both choices can be changed per file, and the preview updates right away. If some characters cannot be decoded, a warning tells you to try another encoding.
The workbook gets sensible column widths, a bold header row that stays frozen at the top while you scroll and, if you like, filter buttons. Files with more than 1,048,576 rows, Excel's limit, continue on extra sheets with the header repeated.
Related tools
Going the other way? Excel to CSV saves sheets with an encoding Excel and other programs read correctly. To use the data in code, try CSV to JSON. For a printable copy, use Excel to PDF, which also accepts CSV files.
Frequently asked questions
Why do my leading zeros disappear in Excel?
Excel converts anything that looks like a number into a number, and numbers cannot start with zero. This tool stores those values as text in the XLSX file, so 00123 and 010-1234-5678 stay exactly as written.
Can I combine several CSV files into one Excel file?
Yes. Drop up to 30 files at once. Each becomes its own sheet, named after the file, in a single workbook called combined.xlsx.
My CSV shows strange characters. What should I do?
The file was probably saved in a different encoding. Encoding detection usually handles it, but you can pick the encoding by hand next to the file and check the preview.
How large can the CSV be?
Files of several hundred MB work on a desktop computer. Parsing runs in a background thread, so the page stays responsive. Phones have less memory, so very large files may fail there.
Are formulas in the CSV executed?
No. Text such as =SUM(A1:A3) is stored as plain text, which also protects you from formula injection in exported data.