How to open a CSV file
A CSV is a table written as plain text: one line per row, values separated by a comma or a semicolon. Anything can open it, from Notepad to Excel, but almost every program damages something on the way. Here is how to open a CSV so that you see the table as it really is.
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What is inside a CSV
Open a CSV in Notepad and you see the file itself: the first line is usually the header, then the records, with a delimiter between values. All you really need to know about the file is its delimiter and its encoding. Those are the two things programs trip over.
Ways to open it
| Tool | What happens |
|---|---|
| Excel, double-click | Often everything lands in one column, accented characters are garbled, and codes with leading zeros turn into numbers |
| Excel, Data → From Text/CSV | Correct, provided you set the encoding, the delimiter and the type of each column by hand |
| Google Sheets | The file has to be uploaded to the cloud; the limit is 10 million cells |
| Notepad, Notepad++, VS Code | You see text but not a table; a large file opens slowly |
| A browser-based viewer | Drop the file into the window: the delimiter and encoding are detected, columns line up, codes stay text |
Types are decided by sampling the values: ZIP codes, SKUs and long identifiers stay text, amounts become numbers, and dates become dates — day-first, month-first and ISO forms such as 15.01.2025 and 2025-01-15 are recognized. Be careful with a purely numeric day and month such as 01/02/2025: it is ambiguous by nature, and the unambiguous ISO form is the safe choice when you produce files.
If the CSV is large
Excel shows no more than 1,048,576 rows and thinks for a long time on hundreds of megabytes. Here the file is read in parts, so millions of rows open as well — see how to open a large CSV.
Getting Excel out of it afterwards
Filter the rows you need and choose Export → Excel (.xlsx): dates land as dates, numbers as numbers, codes as text. That is how a CSV reaches Excel without the surprises of double-clicking it.
FAQ
Why is everything in one column in Excel?
Excel expects the delimiter set by the Windows regional settings, and the file uses another. Details in CSV opens in one column in Excel.
Why do I see strange symbols instead of letters?
The file is in one encoding and was opened in another. See CSV encoding.
Can I edit a CSV?
Yes: turn on editing, change the cells and save — the file is written in the same encoding and with the same delimiter.
Free for personal use. Your file is not uploaded to a server. Windows version — 3.5 MB, no installation: details. Organizations: license.