Canonical Tag FAQ
The most common canonical tag questions, answered.
Quick, plain-English answers to the questions people ask most about the canonical tag and rel=canonical. Each answer links to the full guide or reference where it helps.
Canonical tag basics
What is a canonical tag?
A canonical tag is the rel="canonical" link element placed in a page's <head>. It tells search engines which URL is the preferred version to index when the same or similar content is reachable at more than one URL.
What is a canonical URL?
A canonical URL is the single preferred address a search engine indexes and ranks for a set of duplicate or near-duplicate pages. The canonical tag is how you point at it.
What does “canonicalized” mean?
It means a URL has been resolved to its preferred, standard form so search engines index one version instead of several. The word comes from computer science, where “canonical” is the simplest, standard form of something.
Is the canonical tag a directive or a hint?
A hint. Google weighs your rel="canonical" alongside other signals — redirects, sitemaps, internal links, HTTPS — and can select a different canonical than the one you declared.
Is the canonical tag important for SEO?
Yes. It consolidates duplicate signals so ranking strength is not split across several URLs, and it influences which URL appears in search results. Most technical SEO audits check canonicals for exactly this reason.
Adding and using canonical tags
Where does the canonical tag go?
In the <head> of the HTML, or as an HTTP Link header for non-HTML files such as PDFs. A canonical tag placed in the <body> is ignored.
How do I add a canonical tag in HTML?
Add <link rel="canonical" href="https://www.example.com/page/"> inside the <head>. See the how to add a canonical tag in HTML guide for step-by-step examples.
Should every page have a canonical tag?
A self-referencing canonical on every indexable page is recommended as a baseline. It is not strictly required, but it removes ambiguity from parameter and variant URLs.
Should a canonical URL be absolute or relative?
Absolute. Google recommends canonical URLs that include the scheme and domain (for example https://www.example.com/page/) rather than relative paths.
Can I add a canonical tag without a plugin?
Yes. In raw HTML you place the tag by hand; in WordPress you can use the get_canonical_url filter in code. See canonical tags in WordPress.
Can I add a canonical tag with JavaScript?
It is possible but not recommended. A server-rendered canonical is more reliable; if you inject one with JavaScript it must match the intended URL exactly, and there must be only one per page.
Troubleshooting canonical issues
Why did Google choose a different canonical than mine?
Because rel="canonical" is a hint. Conflicting signals — a redirect, sitemap entry, or internal links pointing elsewhere — or a weak target can lead Google to pick another URL. See user-declared vs Google-selected canonical.
What does “Duplicate without user-selected canonical” mean?
Google found the page to be a duplicate but you declared no canonical, so it chose one for you. See the full explanation.
What does “Alternate page with proper canonical tag” mean?
Your page correctly points its canonical at another URL, and Google is consolidating it as intended. It is informational, not an error. See the details.
Can I use a canonical tag and noindex together?
No — they send contradictory instructions and Google advises against combining them. Use one or the other. See canonical and noindex.
Does a canonical tag pass ranking signals like a redirect?
Google consolidates ranking signals onto the canonical URL, so in effect it behaves similarly to a 301 redirect — but it remains a hint, whereas a 301 is a much stronger signal.
Canonical tag or 301 redirect — which should I use?
Use a 301 redirect when the old URL should disappear and users should never see it; use a canonical when both URLs must stay reachable but only one should be indexed. See canonical tag vs 301 redirect.
Platforms and checking
Does WordPress add canonical tags automatically?
Yes, on singular posts and pages. Archives, the homepage, and taxonomy pages need an SEO plugin such as Yoast or Rank Math. See canonical tags in WordPress.
Does Shopify add canonical tags?
Yes, automatically, and it folds collection-scoped product URLs to the clean /products/ URL. See canonical tags in Shopify.
How do I check a page’s canonical tag?
View the page source and look for <link rel="canonical">, use Search Console’s URL Inspection tool, or run it through the Canonical Tag Checker.