How to open CSV files on a Mac (and fix columns, accents and decimals)
CSV looks like the simplest format there is: rows of text, values separated by commas. In practice it is the source of endless small disasters. Everything lands in column A. Accented letters turn into é. Prices of 1,50 become 150. Leading zeros vanish from postcodes.
This guide explains the three things that go wrong, how to open a CSV correctly on a Mac with or without Excel, and how to save one that others can open.
Updated
Why CSV files open wrong
1. The delimiter
Despite the name, many CSV files are not comma-separated. In countries that write decimals with a comma (Italy, Germany, France, Spain and many more), Excel exports CSV with semicolons. Other systems use tabs or vertical bars. If the app guesses the wrong delimiter, every row ends up in a single column.
2. The text encoding
A CSV file does not say which character encoding it uses. Modern files are usually UTF-8, but exports from older Windows software are often Windows-1252, and some tools write UTF-16. Read with the wrong encoding, é becomes é and € becomes nonsense.
3. The decimal separator
1,500 means one and a half in Italy and one thousand five hundred in the US. If the app reads numbers with your Mac's convention instead of the file's, values are silently wrong, which is worse than a visible error.
The easy way: an app that detects all three
Foglio is a free, open-source spreadsheet app for the Mac that looks at the file before importing it:
- Delimiter: chooses between comma, semicolon, tab and vertical bar by checking which one splits the first rows most consistently, ignoring separators inside quotes.
- Encoding: reads UTF-8 (with or without a byte-order mark) and UTF-16, and falls back to Windows-1252 for older Western European exports.
- Decimals: works out whether the file writes
1.234,56or1,234.56and reads every number accordingly, whatever your Mac's region. - Safety: text that starts with
=is kept as text, never run as a formula, so a malicious CSV cannot trigger calculations.
Steps
Download Foglio, then right-click the .csv file and choose Open With ▸ Foglio. .tsv and .txt files work the same way. When you are done, save it as an Excel workbook (.xlsx) to keep formulas and formatting, or as CSV again.
Other ways to open a CSV on a Mac
- Numbers: double-click or Open With ▸ Numbers. It works well for clean UTF-8 comma files; with semicolons or other encodings, check the import settings and the result carefully.
- Excel: use Data ▸ Get Data ▸ From Text/CSV (or the older From Text wizard) instead of double-clicking, so you can choose the delimiter, the encoding (File Origin) and the column types.
- LibreOffice Calc: shows a Text Import dialog where you choose character set, separators and column types. Very thorough.
- Google Sheets: File ▸ Import ▸ Upload, with automatic or custom separator detection. Requires uploading the data.
- TextEdit: not a spreadsheet, but useful for checking what is really inside the file.
Keep leading zeros and long numbers
Postcodes, product codes and phone numbers like 00123 look like numbers to any spreadsheet and lose their zeros. Long IDs such as card or IBAN-like numbers get rounded beyond 15 digits. If these columns matter, ask for the export with those values in quotes and a prefix, open the CSV in an app that lets you set columns to Text during import (Excel's import wizard, LibreOffice), or keep the original file untouched for reference.
Saving a CSV others can open
CSV holds only the values of one sheet: no formulas, formatting or other sheets. Foglio warns you before saving and offers to save as an Excel workbook instead. When you do save CSV, Foglio writes UTF-8 with a byte-order mark (so Excel recognizes the encoding) and uses ; as the delimiter on Macs set to a decimal-comma region, like Excel does.
If the file is going to someone in another country, tell them which delimiter and decimal separator you used, or send an .xlsx instead. It avoids every problem on this page. For Excel files, see how to open xlsx files without Excel.