UTF-8 vs Shift-JIS CSV
UTF-8 is the broad modern default; Shift_JIS is a legacy Japanese encoding still required by some domestic systems.
Use UTF-8 unless the receiving system explicitly requires Shift_JIS. UTF-8 represents far more characters consistently across platforms. Shift_JIS can be necessary for older Japanese software, but automatic detection is imperfect and some characters cannot round-trip cleanly.
Open the CSV Encoding FixerWhen UTF-8 is the better choice
UTF-8 supports Japanese, Latin text, emoji, and most writing systems in one file. It is the normal choice for web applications, databases, APIs, and modern import tools.
A UTF-8 BOM can help Excel recognize the encoding, although the BOM is not required by UTF-8 itself.
Why Shift_JIS still appears
Older Japanese Windows software, accounting products, and government or partner systems may document Shift_JIS as the required upload format.
The encoding uses variable-width byte sequences and covers a narrower character set, so vendor-specific characters and lookalike symbols can create compatibility surprises.
Detection and conversion limits
A byte sequence can sometimes be plausible under more than one legacy encoding. That is why a detected Shift_JIS result should be treated as a likely answer and verified visually.
Converting to UTF-8 preserves the decoded characters; it does not translate Japanese, normalize names, or restore text that was already lost.
How to fix it safely
- Check the receiving system's documented encoding requirement.
- Preview the untouched source using automatic detection.
- Manually select Shift_JIS if the Japanese preview is wrong under UTF-8.
- Use UTF-8 for the new file unless the receiver specifically requires Shift_JIS.