How do UTF-8 and Big5 differ in their effects on search rankings and user experience?

The available material does not establish that UTF-8 improves search rankings more than Big5; the clearer reasons for choosing UTF-8 concern readability and technical compatibility. A forum author observed that both encodings could achieve good rankings, but this is not an official conclusion from a search engine. UTF-8 may be the preferred choice for new sites or redesigns. Existing Big5 sites, however, should not switch solely in the hope of improving rankings; they should first check for garbled text and inconsistent encoding settings across their systems.

No obvious ranking difference does not prove identical treatment

The author of a PTT discussion about SEO reported finding no particularly significant ranking differences between UTF-8 and Big5 after analyzing the top 100 results for keywords. Other replies also suggested that Big5 was not at a ranking disadvantage. However, the supplied excerpts do not explain how the keywords were selected, the sample size, or the analytical method. This can therefore only be treated as the author’s observation, not as grounds for claiming that all search engines disregard encoding.

The same post speculated that garbled text might cause readers to leave and that a higher bounce rate might in turn affect rankings. No direct verification accompanied this claim. “Content that is difficult to read” should be distinguished from “a decline in search rankings”: the former is an identifiable usability issue, while these materials do not establish a causal link to the latter.

The key to user experience is whether text can be interpreted correctly

A 2022 Welly article explains that Charset specifies the character encoding a browser uses to display a webpage, and that incorrect settings can cause garbled text. This supports the need for correct encoding settings—not the claim that using UTF-8 alone prevents garbled text.

A request for help on Mobile01 offers a concrete example: uploaded images that had previously supported Chinese filenames later had their names displayed as question marks. A respondent suggested checking whether the character encoding used by PHP to display data matched the encoding used by MySQL to store it. This was troubleshooting advice for that particular case, not a confirmed diagnosis, and it does not establish that Big5 was the root cause.

New and existing sites may need different priorities

• New sites or redesigns: The PTT author recommended UTF-8 to reduce the likelihood of readers encountering garbled text. Another reply warned that Big5 might have compatibility issues with newer JavaScript libraries, but provided no versions or reproducible examples, so compatibility still needs to be checked case by case.
• Existing Big5 sites: Some participants in the same discussion felt that continuing to use Big5 was acceptable and that user convenience should come first. This differs from replies advocating discontinuing Big5 and should not be presented as a consensus.
• Sites already displaying garbled text: First check that the webpage’s encoding declaration, the application’s display settings, and the data storage settings match, rather than treating an encoding change as a shortcut to better rankings.