Key points
The canonical URL is the address Google keeps as the reference version among several identical or very similar pages. You indicate it with a rel="canonical" tag, a redirect or the sitemap. Google treats it as a hint: it can choose another URL if your signals contradict each other.
- Redirects and the canonical tag are strong signals; the sitemap is a weak signal (Google, July 10, 2026).
- Several canonical tags on the same page: Google ignores them all.
- Check the canonical chosen by Google in the URL Inspection tool in Search Console.
What is a canonical URL?
For Google, a canonical URL is the URL it chooses as the most representative of a group of duplicate pages. Google’s documentation on the topic (updated on August 20, 2026) calls this choice canonicalization. The canonical page is crawled most regularly. Duplicates are crawled less often, to reduce the crawling load.
The canonical tag is the tool that lets you express your preference. This <link rel="canonical"> element was standardised in April 2012 by the IETF’s RFC 6596. The main search engines recognise it.
<head>
<link rel="canonical" href="https://www.example.com/trail-shoes/">
</head>Example: /trail-shoes/, /trail-shoes/?sort=price and /trail-shoes/?utm_source=emailing show the same list. All three URLs should declare /trail-shoes/ as canonical.
When should you define a canonical URL?
As soon as the same page exists at several addresses, most often unintentionally. Google cites five common origins. Not all of them are solved with a canonical tag:
| Origin | Example | Usual treatment |
|---|---|---|
| Site features | Sorting, filters, tracking parameters | Canonical to the page without parameters |
| Device variants | A separate mobile version (m.example.com) | Responsive site, otherwise canonical to the main version |
| Regional variants | One page for France and one for Belgium, in the same language | hreflang, and a canonical in each language |
| Protocol variants | http:// and https://, with or without www | 301 redirect rather than a canonical |
| Accidental variants | Accessible staging or demo version | Password rather than a canonical |
The same document makes it clear: some duplicate content is normal and does not break the spam policies. The SEO Starter Guide confirms there is no manual action for it. The real cost lies elsewhere: wasted crawling, scattered signals, the wrong version displayed. Causes, detection and other remedies are covered in our article on duplicate content.
How do you tell Google the canonical URL?
Google’s dedicated documentation (How to specify a canonical URL, July 10, 2026) ranks the methods by signal strength:
| Method | Signal strength | When to use it |
|---|---|---|
| 301 redirect | Strong | The duplicate URL does not need to remain accessible |
rel="canonical" tag | Strong | Both URLs must remain accessible (filters, parameters, variants) |
Link: rel="canonical" HTTP header | Strong | Non-HTML files, such as a PDF |
| Inclusion in the sitemap | Weak | As a complement, never on its own |
When an old URL has to disappear, the 301 redirect remains the cleanest solution. The XML sitemap lists only canonical URLs, to avoid any contradictory signal.
The self-referencing canonical
Google recommends a canonical tag on the canonical page itself, pointing to its own URL. It neutralises variants created by parameters added from outside, such as a campaign link. Use an absolute URL, with the protocol and the domain.
In WordPress
WordPress and the common SEO plugins, such as Yoast SEO, generate a self-referencing canonical on each piece of content. The “Canonical URL” field in Yoast’s Advanced tab lets you set a different one, page by page. Check that a theme or a second plugin does not add another one.
Is the canonical tag always respected?
No. Google says so explicitly: indicating a canonical preference is a hint, not a rule. It compares your signals: tag, redirects, sitemap, internal links, preference for HTTPS. Then it keeps the URL it considers best for the user.
Takeaway
A canonical works when all the signals agree. Internal links, sitemap, redirects and tag all point to the same URL.
The Fix canonicalization issues page (updated on August 21, 2026) lists the common causes of a different choice. Language variants without hreflang. A canonical tag or redirect misconfigured by a plugin. Server errors that return the same content on several domains. A hacked site. Content syndicated or copied elsewhere. After a fix, Google may keep pages in the same duplicate cluster for up to two weeks.
Which mistakes should you avoid with the canonical tag?
Many mistakes come from templates or plugins, as Google itself points out. The seven below are documented by Google. They appear in its current documentation and in a 2013 blog post that still holds on these points:
- Declaring several canonicals on the same page, often one per plugin: Google ignores them all.
- Pointing to a page in error (404, soft 404): the target must exist and respond normally.
- Pointing to a noindex page: the two signals contradict each other. Google also advises against using noindex to choose a canonical within a site.
- Canonicalising an entire pagination to page 1: the documentation on pagination asks for each page to have its own canonical.
- Writing a relative URL by mistake:
example.com/pagewithout a protocol is read as a relative path. - Placing the tag outside the <head> or injecting it only with JavaScript. Google recommends putting it in the HTML source code.
- Canonicalising with robots.txt or the URL removal tool. The first prevents the page from being read, the second hides all versions.
Warning
A canonical pointing to a page that is not a true duplicate will probably be ignored, for example from an article to its category. And if it is followed, the original page disappears from the index.
How do you check a site’s canonical URLs?
- Inspect the key pages: in Google Search Console, URL Inspection shows the “User-declared canonical”. It also shows the “Google-selected canonical”. A gap between the two is the first warning sign.
- Read the page indexing report: the duplicate-related statuses group the URLs concerned, such as “Alternate page with proper canonical tag”. See Google indexing.
- Crawl the site: Screaming Frog (Canonicals tab) spots canonicals that are missing, multiple, relative or pointing to a non-indexable page.
- Check consistency: internal links, sitemap and hreflang must target the canonical URLs, not their variants.
- Fix at the source: adjust the theme or plugin rather than each page. Inspect again after a few days.
The canonical URL is part of technical SEO: the full topic is in technical SEO. To place this setting among the other page optimisations, see on-page SEO and the SEO guide.
Frequently asked questions
What does canonical mean?
“Canonical” refers to the <link rel="canonical"> tag. Placed in the head of a page, it tells search engines which version is the reference. It is used when several addresses show the same content.
What is the difference between a canonical URL and a 301 redirect?
A redirect sends visitors and robots to another URL: the old one can no longer be viewed. A canonical leaves both URLs accessible and only indicates which one to index. Both are strong signals for Google.
Does every page need a canonical tag?
Yes, that is the recommended practice. Every indexable page carries a canonical, self-referencing if the page is itself the reference version. Google explicitly recommends the self-referencing canonical.
Can you use a canonical across two domains?
The tag accepts a URL on another domain, and Google treats it as one hint among others. For content syndicated on a partner site, Google does not recommend it. The most effective option: the partner blocks the indexing of its copy.
How long does Google take to take a canonical into account?
As long as it takes to recrawl the pages concerned and confirm the new canonical URL. Google states that it may keep pages in the same duplicate cluster for up to two weeks after a fix.
Sources
- Google Search Central, What is canonicalization, updated on August 20, 2026. Accessed on September 24, 2026.
- Google Search Central, How to specify a canonical URL with rel=”canonical” and other methods, updated on July 10, 2026. Accessed on September 24, 2026.
- Google Search Central, Fix canonicalization issues, updated on August 21, 2026. Accessed on September 24, 2026.
- Google Search Central Blog, 5 common mistakes with rel=canonical, published on April 8, 2013. Accessed on September 24, 2026.
- Google Search Central, Pagination, incremental page loading, and their impact on Google Search, updated on December 10, 2025. Accessed on September 24, 2026.
- Google Search Central, Search Engine Optimization (SEO) Starter Guide, updated on December 10, 2025. Accessed on September 24, 2026.
- IETF, M. Ohye and J. Kupke, RFC 6596, The Canonical Link Relation, April 2012. Accessed on September 24, 2026.
Digital marketing, SEO and GEO consultant
Article checked and updated by the author. Sources consulted on the date shown.
Cite this article
, . (2026, September 26). Canonical URL: how Google chooses it. Elev8 Lab. https://elev8-lab.fr/en/seo/canonical-url/