Google repeated its hyphen advice. Should you rename your underscore URLs?

KEY TAKEAWAYS

1. Google reads underscore-joined words as one word, and it has said so consistently since at least 2011.
2. The same Google sources call URL words a tiny signal that fades once a page has content.
3. Renaming live URLs is a site move with weeks to months of reprocessing and a year of redirects.
4. Use hyphens going forward, and fold old renames into a migration you already have planned.

Google has spent October talking about URLs. On 14 October 2026 it launched a video series called The Non-Canonical Cabinet, and the first episode covered what can go in a URL. Gary Illyes said Google reads words joined by underscores as one long word and recommends hyphens. A week later Google edited its URL structure guide to match. The changelog entry, dated 23 October, says the edit was made to sync the documentation with the video series.

SEO audit tools already flag underscore URLs, and new guides on the subject appeared within days. The real question for most sites is not which separator is better. It is whether renaming URLs that already exist is worth what it costs. Google's own documentation answers that more clearly than the coverage has.

What did Google actually change?

The wording, not the advice. Google has recommended hyphens over underscores for years. Search Engine Roundtable compared the old and new text on 21 October. The old version said underscores were not recommended because that style was already used for concepts kept together, with format_date as the example. The new version says underscores are commonly used that way and adds that hyphens clearly mark a word boundary.

PPC Land pointed out before the edit that the document and the video gave different reasons. The document gave a historical one. The video described how Google actually reads the URL. The edit brings the two closer together. The current version also has a section on case sensitivity, noting that Google treats /APPLE and /apple as two different URLs.

How does Google read an underscore? The answer has barely moved

This is one of the oldest settled questions in technical SEO. Here is the record.

• 2004. A forum member built a test page with nonsense words in its file name. Search Engine Roundtable reported that segments joined by underscores did not match searches, while segments split by hyphens did. It was one page and an early result.
• July 2007. Matt Cutts said at WordCamp that Google would start treating underscores and dashes the same.
• August 2007. Cutts said it was not a done deal. Sites already using underscores did not need to rebuild, and new sites should still pick dashes.
• April 2009. Stephan Spencer reported the change still had not happened.
• 2011. In a Google video covered by Search Engine Land, Cutts said Google still joined words on underscores and split them on dashes. He called switching existing URLs a second-order effect. A Bing spokesperson said Bing's URL ranking features did not tell the two apart.
• April 2024. In Google's office hours, Illyes said keywords in URLs contribute very little to ranking, but he still preferred hyphens.
• October 2026. Illyes repeated the one long word explanation and added that this can sometimes be fine.

So the 2007 promise never shipped. Some current guides, such as Hydrogen SEO, say Google handles underscore URLs fine in practice. That is not quite right about the mechanism, since Google joins the words. It is close to right about the effect, for reasons the next section covers.

How much is the separator worth?

Very little, by Google's own account. Illyes called URL keywords an "incredibly small signal" in the October episode. He said they matter mainly when Google has nothing else to go on, such as a new site with no content, and become close to irrelevant once Google sees the page. John Mueller called them a very small factor in 2016 and a very lightweight one in 2021. Google's SEO Starter Guide says keywords in the URL path have hardly any effect beyond showing up in breadcrumbs.

The separator only changes how those words are split. If the words themselves carry almost no weight once content exists, the way they are split carries less.

Some top-ranking guides claim more. WooRank wrote in 2023 that URL structure can be decisive. Others promise a ranking lift or higher click-through. The only recent test data we found is a table from Textkit, published in May 2026, comparing three identical articles on three demo domains over 90 days. The hyphen version averaged position 11.2 and the underscore version 14.7. Three different domains is the problem. Any difference between the domains is mixed into the result, and the article publishes no other test data. It does not outweigh fifteen years of consistent statements from Google.

The click-through argument is weaker than it was, too. Since 23 January 2025, Google's mobile results show only the domain in the visible URL, not the path. Desktop still shows a domain and breadcrumb trail. On a phone, nobody sees your separator.

What does renaming cost?

Google does not treat a path rename as a small edit. Its site move guide covers URL path changes on the same domain alongside domain and protocol moves.

• Rankings may fluctuate while Google recrawls and reindexes the site.
• For a medium site, new URLs can take a few weeks or more to replace old ones in results. Larger sites take longer.
• Redirects should stay for as long as possible, generally at least a year.
• Internal links, sitemaps, canonical tags and hreflang all need to point at the new URLs.
• Redirect chains should be avoided. Google follows up to 10 hops but advises keeping chains to about 3.

At Search Central Live in Barcelona on 2 October 2026, Illyes showed typical timings, as recorded in an attendee recap reported by PPC Land. A site move typically took one to three months, and the slowest took six months to a year or more. A canonical change typically took one to three weeks. The recap gives no method or sample behind those figures, so treat them as Google's rough expectations.

Mueller's view has been blunt. In September 2022 he said changing URLs for SEO reasons usually brings some risk and no gain, with a likely temporary setback while Google reprocesses the site. Our content pruning piece shows what redirects leave behind years later: chains, stale internal links and URLs pointed at loose matches.

When should you switch? A decision by situation

The fourth row is where most advice goes wrong. Several guides say to rename underscore URLs if they are underperforming. That assumes the separator is the cause. Google's statements say it almost never is, once a page has a title, headings and body text. Renaming an underperforming page adds a reprocessing period on top of whatever the real problem was.

Linkilo suggests starting with your most important pages on a large site. We would do the reverse if you rename at all. Google's site move guide says large sites can move one section at a time to make problems easier to spot. Start with a low-value section, watch it, then decide.

A worked example with invented numbers

This is hypothetical. A content site has 900 posts. About 300 older posts have hand-typed slugs like /blog/payroll_tax_guide. A replatform is planned for the first quarter of next year, and the new platform will change every URL from /blog/ to /guides/ anyway.

Option one is to rename the 300 now. That is a site move for 300 URLs this quarter, then a second move for all 900 next quarter. The 300 go through two redirect hops unless the team rewrites the first set of redirects. Two reprocessing periods, each of one to three months by Google's typical range, for a signal Google calls incredibly small.

Option two is to wait. In the replatform, /blog/payroll_tax_guide redirects straight to /guides/payroll-tax-guide. The redirect already had to exist. Fixing the separator adds no extra URL changes, no extra hop and no extra reprocessing. Meanwhile the CMS slug rule is switched to hyphens today, so the 300 do not become 350.

The second option gets the same end state for the cost of one setting change.

If you do rename, how do you do it safely?

1. Find the URLs. In Search Console's Performance report, filter pages with URLs containing an underscore. Add clicks and linking domains from your other tools.
2. Fix the source first. Change the slug rule, theme setting or import script that creates underscores, so new URLs are clean before old ones move.
3. Map one to one. Each old URL redirects with a 301 straight to its final hyphenated URL. Never to a category or home page.
4. Keep one live form. Only the hyphenated URL should return 200. Google treats URLs as distinct strings, the same reason encoded and unencoded forms can split your pages. Pick one case as well.
5. Update everything that points at the old URL. Internal links, sitemaps, canonical tags and hreflang. Google's canonical guide says to link internally to the canonical URL.
6. Start small. Move a low-value section first and wait a few weeks before the next batch.
7. Leave redirects in place. At least a year, per Google's guide, and longer if external links point at the old URLs.

What should you take from the October noise?

Google has not changed how it treats underscores. It has changed how clearly it explains them. Use hyphens for everything new. Fix the setting that makes underscores. Leave ranking pages alone unless they are moving for another reason. If a rank tracker shows a drop after a rename, check whether the data is real before you undo anything.

If you want a technical check of how your site is crawled and seen in search and AI answers, join the waitlist or write to esh@ethosengine.io.

Questions

Does Google treat underscores and hyphens the same in URLs?

No. Gary Illyes said in October 2026 that Google reads words joined by underscores as one long word, and Google's URL guide recommends hyphens. The 2007 claim that the two would be treated equally never shipped. Bing said in 2011 that its URL ranking features do not tell them apart.

Will changing underscores to hyphens improve my rankings?

Probably not in any way you could measure. Google calls keywords in the URL path a very small signal that matters mostly before it has seen a page's content. A page with a title, headings and body text already tells Google what its words are.

What is the risk of renaming URLs from underscores to hyphens?

Google treats a path change as a site move. Its guide warns of ranking fluctuations while pages are recrawled, says redirects should stay for at least a year, and a Google talk in October 2026 put a typical site move at one to three months.

When is it worth switching to hyphens?

For every new URL, for templates that will generate future URLs, and during a migration where the URLs are changing anyway. In those cases the extra cost is close to zero. Renaming pages that already rank, only to change the separator, is the case to avoid.

Sources

1. Google Search Central, URL structure best practices for Google Search developers.google.cn
2. Google Search Central, Latest Google Search documentation updates developers.google.com
3. Google Search Central, Site moves with URL changes developers.google.com
4. Google Search Central, Redirects and Google Search developers.google.com
5. Google Search Central, How to specify a canonical URL with rel=canonical and other methods developers.google.com
6. Google Search Central, SEO Starter Guide developers.google.com
7. Google Search Central Blog, Simplifying the visible URL element on mobile search results developers.google.cn
8. Google Search Central, April 2024 Google SEO office hours developers.google.com
9. Search Console Help, Performance report advanced filtering and comparison support.google.com
10. Search Engine Roundtable, Google updated its URL structure best practices for hyphens in URLs seroundtable.com
11. Search Engine Roundtable, Google on what you can put in URLs seroundtable.com
12. Search Engine Journal, Google launches a video series for odd technical SEO questions searchenginejournal.com
13. PPC Land, Google says URL keywords become irrelevant once a page has content ppc.land
14. PPC Land, Google says new pages take about 20 hours to be found, some never are ppc.land
15. Search Engine Land, Google and Bing (still) handle underscores and dashes differently searchengineland.com
16. Search Engine Land, URL changes are not so simple for Google Search searchengineland.com
17. Search Engine Roundtable, Hyphens and underscores are now treated equally in Google seroundtable.com
18. Search Engine Roundtable, Matt Cutts of Google says still go with dashes in URLs seroundtable.com
19. Search Engine Roundtable, Underscores versus hyphens, a Google test seroundtable.com
20. Search Engine Roundtable, Google really wants you to avoid changing URLs just for SEO reasons seroundtable.com
21. Search Engine Roundtable, Google keywords in URLs a very small ranking factor seroundtable.com
22. Search Engine Journal, Are URLs a Google ranking factor searchenginejournal.com
23. Stephan Spencer, Underscores still not word separators stephanspencer.com
24. Hydrogen SEO, Underscores in URL. Should you fix it hydrogenseo.com
25. Textkit, Dash vs underscore URL textkit.tech
26. WooRank, URL best practice. Hyphens, underscores, or no separators woorank.com
27. Linkilo, Hyphens or underscores in URLs linkilo.co
28. Australian Internet Advertising, Hyphen vs underscore in URLs aiad.com.au
29. SiteGuru, Underscores vs hyphens in URL siteguru.co
30. Clickmatix, Hyphens vs underscores. URL SEO best practices clickmatix.com.au
31. iTechGuides, Hyphens vs underscores in URLs itechguides.com

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