Canonical Tags Explained: Pointing Google to the Right URL

The same content can sometimes be reached through more than one web address. A product might appear under several category paths. A page might load with tracking parameters on the end. To search engines, each address can look like a separate page. A canonical tag tells them which one you consider the main version.

What a canonical tag looks like

It is a line in the page's head:

<link rel="canonical" href="https://www.example.com/blog/my-article/">

The href is the preferred, "canonical" URL for that content.

Why it matters

When several URLs show the same or very similar content, search engines choose one to show and may combine signals from the others. A canonical tag helps you influence that choice, so the version you want is the one that appears, and so ranking signals are not split across duplicates. See duplicate content and SEO.

It is a hint, not a command

Google treats the canonical tag as a strong hint, not an order. It may choose a different URL if other signals, such as redirects, internal links, and sitemaps, point elsewhere. So keep your signals consistent.

When you need one

• Tracking parameters and filters, such as ?utm_source= or sort options
• Multiple paths to the same product or article
• HTTP vs HTTPS, www vs non-www. Redirect these rather than relying only on a canonical tag. See 301 redirects
• Syndicated content. If you republish content elsewhere, a canonical pointing to the original helps
• Printer-friendly or alternative versions of a page

Best practices

1. Add a self-referencing canonical on every indexable page, pointing to its own preferred URL.
2. Use absolute URLs, including the protocol and domain.
3. Point to a page that returns a normal, successful response, not an error or a redirect.
4. Keep one canonical per page. Conflicting tags confuse search engines.
5. Match your other signals. Link internally to the canonical URL, and list it in your sitemap.
6. Do not canonicalize to unrelated pages. A canonical should point to equivalent content.

Common mistakes

• Pointing every page's canonical to the homepage
• Canonical tags that point to a redirected or deleted URL
• Mixing up canonical and noindex. They do different things. See noindex and nofollow
• Different canonical URLs in the HTML and in HTTP headers
• Paginated pages all pointing to page one

How to check

Use the URL Inspection tool in Search Console to see which URL Google selected as canonical. View page source to confirm your tag.

Most platforms handle it for you

WordPress, Shopify, and many site builders add canonical tags automatically, and many SEO plugins let you customize them. Still, check a few pages. For a broader checklist, see technical SEO.

The bottom line

Use canonical tags to nominate the preferred version of duplicate or near-duplicate pages, and keep your redirects, links, and sitemaps in agreement.