Why do Chinese characters turn into gibberish when I double-click a CSV in Excel?

Question

Weirdo · Accepted Answer

Because Excel didn't read the file as UTF-8. If a UTF-8 CSV has no BOM (byte order mark) at the start, double-clicking it can make Excel fall back to another character set, and Chinese text turns into gibberish.

The BOM is a special character (U+FEFF) placed at the very beginning of a file; in UTF-8 it is the three bytes EF BB BF, signalling “this is Unicode”. Wikipedia notes the BOM is optional in UTF-8 and not required by the Unicode standard, but plenty of Windows software treats it as the signal. Microsoft says it plainly: a UTF-8 CSV saved with a BOM opens normally in Excel.

Microsoft's advice is to skip the double-click and import instead: in Excel go to Data > Get Data > From File > From Text/CSV, or use the “Get Data From Text” Text Import Wizard (a legacy feature you may need to enable in Options). Step 1 of the wizard has a File origin setting; pick the character set that matches the file, which here means UTF-8. Microsoft says the default is fine in most cases, but if the file was created with a different character set than your computer uses, change it manually.

When your program or system exports a CSV, saving it as “UTF-8 with BOM” is the easiest way to let recipients open it by double-click. Wikipedia does warn that a BOM can trip up software that doesn't expect non-ASCII bytes at the start of a file, so consider who else will consume it.

Why do Chinese characters turn into gibberish when I double-click a CSV in Excel?

A BOM is a signature at the start of the file

No BOM? Import it instead of double-clicking

If you're the one exporting the file