If you run a WordPress blog, a small business site or a client portfolio, you have probably wondered whether the underscores in some of your URLs are hurting you. Google recently touched its URL documentation on exactly this point. This guide is for site owners and marketers who want to know what the page says, what it does not say, and whether any action is needed.
What changed in Google’s documentation
Google’s Search Central updates page lists an entry dated October 23, 2026, saying the URL structure best practices were updated “to clarify word separation guidelines using hyphens versus underscores.” The same page says the change was made to match episodes of a Google video series. Industry news sites have reported the change too, but everything below is based on Google’s own pages.
An earlier entry in the same changelog, from June 18, 2025, describes a reorganisation of the URL structure documentation “so it has a clearer flow.” That entry was a docs-only change. The October 2026 entry is also described as a clarification of guidance, not an announcement of new behaviour.
What the official page says about hyphens and underscores
On the current “URL structure best practices for Google Search” page, the relevant advice is to use hyphens to separate words. Google recommends hyphens instead of underscores, and gives a reason: “for historical reasons, we don’t recommend using underscores.” The page links this to programming languages, where an underscore is commonly used to join concepts, as in format_date. It also says that running words together with no separator, such as greendress, is not recommended.
Two details matter for how you read this:
- The wording is a recommendation (“we recommend”, “we don’t recommend”). The page does not call underscores an error, and it does not say Google cannot crawl or index them.
- The page does not describe hyphens as a ranking factor. It sits in a section about making URLs easy to understand, alongside advice about descriptive words and readable structure. Nothing on the page says a URL with a hyphen will outrank one with an underscore.
The page has no “last updated” note, so it does not show which sentences changed; this article describes only what it says today.
What makes a good URL, according to the same page
The hyphen advice is one item in a longer list. The page splits its guidance into requirements for a crawlable structure and recommendations for readability. The table below summarises them.
| Topic | What the page says |
|---|---|
| Descriptive words | Prefer readable words over long ID numbers, for example /wiki/Aviation rather than a parameter-heavy index.php URL. |
| Audience language | Use words in the language your audience searches in, with transliterations where they apply. |
| Non-ASCII characters | Percent-encode them in links. The page prefers gem%C3%BCse over gemüse. |
| Word separators | Use hyphens, not underscores, and do not run words together. |
| Parameters | Use as few as you can, and remove any that do not change the content. Use = and & in the standard way. |
| Case | URLs are case sensitive, so /APPLE and /apple are different URLs to Google. Pick one case and keep it consistent. |
| Fragments | Google generally does not support fragments such as /#/potatoes for changing content. Use the History API for JavaScript sites. |
| Multi-regional sites | A country domain or a country subdirectory such as /de/ makes geotargeting easier. |
The same page also warns about structures that create many URLs for the same content, such as stacked filters, session IDs, endless calendars and broken relative links. For most small sites these are bigger risks than an underscore. If you suspect crawl problems, the guide on fixing crawl errors in Google Search Console is a sensible next step.
Should you change existing underscore URLs?
The documentation tells you what to prefer for URLs you create. It does not tell you to rewrite URLs that already exist, and it says nothing that makes underscore URLs a problem to fix urgently. So this part is a judgement call, and the trade-offs are practical rather than official.
Reasons to leave them alone
- Pages that already rank, earn links or get shared have established addresses. Any change adds risk, even when redirects are set up correctly.
- The page frames hyphens as a recommendation, not a requirement, and does not present them as a ranking boost.
- WordPress’s own documentation describes permalinks as permanent URLs that “should never be changed.”
Reasons to change them
- You are already planning a restructure or migration, so redirects will be set up anyway.
- The pages are low-traffic and low-value, so there is little to lose and some tidiness to gain.
A reasonable default for most sites is simple: use hyphens for every new URL, leave established underscore URLs alone, and only convert them as part of a planned clean-up.
If you do change them, use 301 redirects
Google’s page on redirects says that if you need to change which URL appears in search results, permanent server-side redirects are recommended whenever possible. The 301 and 308 status codes both signal a permanent move. A permanent redirect tells Google the target should be treated as the canonical URL, and Google advises using one “when you’re sure that the redirect won’t be reverted.” The page lists server-side redirects, set in server configuration such as .htaccess on Apache or NGINX config, as the method most likely to be interpreted correctly. JavaScript redirects are described as a last resort.
The same page notes that the old URL may linger as an alternate name in results for a while after a move. It does not give a time limit for keeping redirects in place. Here is a cautious workflow, with the steps beyond Google’s redirect advice being general good practice rather than official requirements:
- Export a list of the underscore URLs and decide which are worth changing.
- Map each old URL to its new hyphenated URL on a one-to-one basis. Avoid sending many pages to the home page.
- Create permanent server-side redirects, using your host’s tools, a redirect plugin or server rules.
- Update internal links and your sitemap to the new URLs so you are not relying on the redirect. Our guide to smart internal linking covers how to do this tidily.
- Test a sample of old URLs, then watch the indexing and crawl reports in Search Console for errors.
WordPress permalink settings
In WordPress, go to Settings, then Permalinks. According to the WordPress documentation, the options are Plain, Day and name, Month and name, Numeric, Post name and Custom Structure. The Plain setting produces addresses like example.com/?p=N, which the documentation describes as not user-friendly and not optimised for search engines. WordPress installs with Plain as the default.
For most blogs, Post name is the simplest readable choice. The %postname% tag uses a sanitised version of the post title, which WordPress documents with the example “This Is A Great Post!” becoming this-is-a-great-post. In other words, WordPress separates words with hyphens by default. Underscores usually appear only when someone typed a custom slug, imported content from another system, or built the site on older software.
Be careful with two things:
- Changing the site-wide structure on a live site changes every post URL at once. Only do it with a redirect plan.
- Editing a single slug is done in the post or page’s URL field in the editor. Changing it changes that page’s address, so add a redirect from the old one.
The WordPress permalinks documentation does not promise an automatic redirect when a slug changes, so check what your theme, host or SEO plugin does before relying on one. For a broader look at URL habits, see best practices for URL optimisation.
Common mistakes to avoid
- Treating a documentation clarification as a ranking announcement and rushing a site-wide rewrite.
- Changing URLs without redirects, which leaves visitors and links hitting error pages.
- Using a temporary redirect for a permanent change. Google’s page says temporary redirects leave the source page in results.
Key takeaways
- Google’s changelog lists an October 23, 2026 clarification of hyphen versus underscore guidance in its URL structure documentation.
- The page recommends hyphens to separate words and says it does not recommend underscores “for historical reasons.”
- This is guidance about readable URLs. The page does not present it as a ranking factor or say underscore URLs cannot be indexed.
- Use hyphens for all new URLs. Leave established underscore URLs unless you have a reason to change them.
- If you change URLs, use permanent server-side redirects (301 or 308), update internal links, and monitor Search Console.
FAQ
Does Google penalise underscores in URLs?
The official page does not say so. It recommends hyphens and does not recommend underscores, but it frames this as guidance for readable, understandable URLs. It does not describe a penalty.
Will switching to hyphens improve my rankings?
Nothing on the page promises that. Moving URLs also carries risk, so do not expect a ranking gain from the change alone.
What type of redirect should I use?
Google’s redirect page recommends permanent server-side redirects whenever possible when you need to change the URL shown in search results. Both 301 and 308 signal a permanent move.
Does WordPress use hyphens or underscores?
By default WordPress builds slugs from the post title with hyphens, as in the documented this-is-a-great-post example. Underscores generally come from manual edits or imported content.