Free TXT Encoding Converter: GBK, Big5, Shift_JIS to UTF-8

Convert legacy TXT files to UTF-8 before importing

Old .txt files often come from systems that did not use UTF-8 by default. Chinese novels may be saved as GBK, GB2312, GB18030, or Big5. Japanese text can appear as Shift_JIS or EUC-JP. Korean files may use EUC-KR. Western archives sometimes use Windows-1252 or ISO-8859-1. When those files are opened as UTF-8, the result is garbled text, missing punctuation, or unreadable characters.

This converter helps you repair that workflow before the file reaches WristTale, a Garmin watch, a Markdown editor, or any modern app that expects UTF-8. Drop a TXT file, let the page detect a likely source encoding, preview the converted text, and download a UTF-8 copy.

For original TXT files larger than 10MB, the tool automatically splits the UTF-8 output locally. It prefers chapter boundaries so paragraphs are not cut in the middle; if reliable chapter headings are not found, it falls back to paragraph boundaries. Each split file keeps the book title and is kept under 10MB whenever possible.

If your main goal is reading the file on a watch, start with the Garmin TXT reader workflow, then return here only when the source TXT file is garbled or not UTF-8.

Why UTF-8 is the safest target format

UTF-8 is the default text format for modern web pages, programming tools, mobile apps, and cross-platform document workflows. It keeps English text compact, supports Chinese, Japanese, Korean, emoji, and rare Unicode characters, and avoids byte order problems that can appear in UTF-16 files.

For WristTale users, UTF-8 is also the most practical format for syncing books and notes to a Garmin watch. It makes chapter detection more predictable, keeps storage estimates understandable, and reduces the chance that a phone preview looks different from the watch reading screen.

Supported source encodings

The tool can decode common legacy text encodings directly in the browser:

Automatic detection is a convenience, not a guarantee. If the preview still looks wrong, choose another source encoding manually and convert again. For Chinese TXT novels, GB18030 is a strong fallback because it is a superset-style option for many GB-family files.

If you want to understand how detection works before converting, read How to Detect File Encoding Before Converting TXT to UTF-8.

GBK, GB2312, and GB18030 to UTF-8

If a simplified Chinese TXT novel opens as unreadable symbols, the source file is often GBK, GB2312, or GB18030. Use auto detect first, then manually try GB18030 if the preview is still wrong. GB18030 is usually the safest manual fallback for GB-family TXT files because it covers a broader character range than older GBK or GB2312 files.

Use this workflow for Chinese TXT books, study notes, saved forum posts, and older Windows text files:

1. Select the original .txt file.
2. Convert once with auto detect.
3. If the preview is still garbled, choose GB18030 manually.
4. Download the UTF-8 copy only after chapter titles and body text look readable.

Big5 to UTF-8 for Traditional Chinese TXT

Traditional Chinese TXT files from Taiwan, Hong Kong, Macau, old archives, or older desktop tools may use Big5. When a Big5 file is decoded as UTF-8 or GBK, the result can look like unrelated CJK characters instead of simple replacement marks.

If the text should be traditional Chinese but GB18030 does not look right, choose Big5 as the source encoding and check several paragraphs before downloading. Keep the original file as a backup because automatic detection can confuse short Big5 and GB-family samples.

Shift_JIS and EUC-JP to UTF-8

Japanese TXT archives, game scripts, subtitles, and old notes may use Shift_JIS or EUC-JP. Try Shift_JIS first for older Windows-origin Japanese files, then try EUC-JP if the preview still contains broken kana, odd punctuation, or unreadable CJK text.

This page is still a plain TXT converter. It does not parse subtitle formats, EPUB files, PDFs, or scanned documents. Export clean text first, then convert that text to UTF-8 here.

File encoding detector and manual preview

The built-in detector uses byte-order marks, UTF-16 byte patterns, valid UTF-8 checks, and character-distribution clues to choose a likely source encoding. It also uses jschardet to improve detection for legacy CJK text. Detection is useful, but the preview is the final check.

Before downloading, scan the first chapter, the middle of the file, and the end of the file. If only one section is broken, the TXT may contain mixed encodings or pasted boilerplate from another source. In that case, split the file or re-export clean text before importing it into WristTale.

Private by design

The file is processed on your device. The page reads the file with browser APIs, decodes it locally, and creates a downloadable UTF-8 copy from the converted text. The TXT file is not uploaded to a WristTale server.

This matters for personal notes, paid ebooks you are allowed to process, race manuals, study materials, language-learning lists, and any file that should not leave your computer.

Optional boilerplate cleanup

Some TXT files include repeated site notices, separators, or watermark-like boilerplate around the actual book text. After conversion, the tool checks for obvious blocks and asks before removing anything. Nothing is deleted automatically. If the suggested cleanup is too aggressive, keep the original converted text.

How to use the converted file with WristTale

1. Convert the original .txt file to UTF-8 on this page.
2. Open the downloaded utf8_...txt file on your phone.
3. Import it into WristTale.
4. Preview the detected chapters and edit titles if needed.
5. Sync selected chapters to your Garmin watch.

For the full import and sync workflow, read the WristTale user guide. If you want a more reliable chapter structure, convert the TXT file into Markdown with # Chapter headings before importing.

FAQ

Is this a GBK to UTF-8 converter?

Yes. It supports GBK, GB2312, and GB18030. If you are not sure which one your Chinese TXT file uses, leave source encoding on auto detect first, then try GB18030 manually if the preview is still garbled.

Is it also a file encoding detector?

Yes. The page detects a likely source encoding before conversion, but detection is probabilistic. Always check the preview and manually try another encoding if the text still looks wrong.

Should I choose GBK or GB18030?

For most simplified Chinese TXT files, try auto detect first, then GB18030. GB18030 is the broader fallback. Use GBK or GB2312 manually only if GB18030 produces an unexpected preview.

Can it fix mojibake or garbled Chinese text?

It can fix many cases where the original bytes are still intact but the file was opened with the wrong encoding. It cannot recover text that was already saved after being corrupted by another app.

For a deeper troubleshooting workflow, read How to Fix Garbled Chinese Text and Convert TXT Files to UTF-8.

Does the file upload to a server?

No. Conversion happens in the browser. The selected TXT file stays on the current device.

Why does the downloaded file include a UTF-8 BOM?

The UTF-8 BOM helps some Windows tools recognize UTF-8 text reliably. Most modern apps can read UTF-8 with or without it.

Should I use this for EPUB or PDF files?

No. This page is for plain .txt files. For EPUB, PDF, or scanned documents, use a dedicated converter first and export clean text before preparing the file for WristTale.

Related guides

• How to Fix Garbled Chinese Text and Convert TXT Files to UTF-8
• How to Detect File Encoding Before Converting TXT to UTF-8
• Garmin TXT Reader: Read Text Files and Ebooks on Your Watch
• WristTale user guide