Japanese Slugs in WordPress: Common Problems and Switching to English

This article is a localized edition of the Japanese original. Read the Japanese original

When you create a post with a Japanese title in WordPress, the slug (the last part of the URL) is Japanese too, and the URL looks like %e3%83%af%e3%83%bc…. This is because WordPress converts Japanese into a form that can be used in URLs (percent-encoding), and it is not an error. Browsers often decode it back to Japanese in the address bar, which makes it easy to miss.

Japanese slugs do have some practical drawbacks, though. This article explains what happens, how to switch to English slugs, and what to watch out for when changing published posts. We tested this on WordPress 6.9 and confirmed in the 7.1 source code that the behavior is the same (as of November 2026).

How Japanese slugs are stored

When WordPress builds a slug from a title, sanitize_title_with_dashes() lowercases Latin letters and converts Japanese and other characters into UTF-8 percent-encoding. At that point it cuts the encoded result to 200 characters (sanitize_title_with_dashes()).

Each Japanese character becomes 9 characters, such as %e3%83%af, so for an all-Japanese title the slug is cut after roughly the first 22 characters. When we tried a 40-character title, the slug came out at 198 characters (22 Japanese characters).

Title:  WordPress 日本語 スラッグ
Slug:   wordpress-%e6%97%a5%e6%9c%ac%e8%aa%9e-%e3%82%b9%e3%83%a9%e3%83%83%e3%82%b0

Common issues with Japanese slugs

For search engines, Japanese URLs are not necessarily a disadvantage. Google recommends using words in your audience's language in URLs and says non-ASCII characters should be percent-encoded (Google Search Central: URL structure best practices, as of November 2026). That encoding is exactly what WordPress does automatically. So whether to use Japanese or English slugs comes down mainly to how easy the URLs are to share and manage.

Use English slugs for new posts

In the block editor

1. On the post edit screen, open the "Post" tab in the settings sidebar on the right.
2. Click the current URL in the "Slug" row.
3. Enter a slug using letters, numbers, and hyphens (for example, japanese-slug). Uppercase letters and spaces are converted to lowercase and hyphens when you leave the field.
4. Check the URL shown under "Permalink:" and save the post.

In the Classic Editor

Click the "Edit" button next to "Permalink:" below the title, enter the slug, and click "OK."

Fixing posts from the post list

In Posts → All Posts, hover over a post and open "Quick Edit" to change the "Slug" field.

Category and tag slugs

Categories and tags created with Japanese names also get Japanese slugs. In Posts → Categories (or Tags), enter an English value in the "Slug" field when you create one, or edit it afterward.

For setting the permalink structure itself (such as "Post name"), see How to set up WordPress permalinks.

Find and fix Japanese slugs with WP-CLI

If you have SSH and WP-CLI, you can list Japanese slugs (those containing %).

# List posts and pages whose slug contains %
wp post list --post_type=post --post_status=publish --fields=ID,post_name --format=csv | grep '%'
wp post list --post_type=page --post_status=publish --fields=ID,post_name --format=csv | grep '%'

# Categories and tags
wp term list category --fields=term_id,slug --format=csv | grep '%'
wp term list post_tag --fields=term_id,slug --format=csv | grep '%'

# Change slugs one at a time (replace the IDs with the ones from the list)
wp post update 123 --post_name=japanese-slug
wp term update category 5 --slug=news

Back up your database before changing many slugs at once.

Cautions when changing the slug of published content

Changing the URL of a published post can break old URLs that remain in search results, on other sites, and on social media. How much WordPress handles automatically depends on the content type.

This behavior comes from wp_check_for_changed_slugs() and wp_old_slug_redirect() in WordPress core (wp_old_slug_redirect()). When you change the slug of a page, category, or tag, create a 301 redirect from the old URL to the new one yourself, using the Redirection plugin or your server configuration.

Also do the following:

• Update internal links that point to the old URL so they use the new URL
• Open the old URL with curl -I and confirm that it returns 301 and the new URL

curl -I "https://example.com/%e6%97%a5%e6%9c%ac%e8%aa%9e/"
# Forwarding works if you get HTTP/1.1 301 Moved Permanently and Location: https://example.com/japanese-slug/

If you changed a post's slug but the old URL doesn't forward, see When redirects don't work after changing a post slug for how to investigate.

FAQ

Are Japanese slugs bad for SEO?

Not necessarily. Google recommends using words in your audience's language in URLs. The main reason to switch to English is to make URLs easier to share and manage.

Should I change all published posts to English slugs?

It's safer not to force changes on posts that get search traffic or have external links. If you do change them, set up redirects yourself for pages, categories, and tags, as shown in the table above. Even just using English slugs for new posts makes things easier to manage.

My Japanese slug got cut off. Can I fix it?

Yes. Enter a shorter Japanese or English slug in the slug field. For published posts, the old URL is forwarded automatically.

Summary

• Japanese slugs are stored percent-encoded. It isn't an error, but URLs get long and Japanese is cut off at about 22 characters.
• For new posts, set an English slug in the block editor's "Slug" field or with Quick Edit.
• When you change a published slug, only published posts are forwarded automatically. For pages, categories, and tags, create 301 redirects yourself.

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