What the tag looks like
<link rel="canonical" href="https://www.example.com/services/seo/">
Why duplicate URLs happen
- The same page with and without www, on HTTP and HTTPS, or with and without a trailing slash
- Tracking parameters, such as
?utm_source=newsletter - Filters and sorting options in online shops
- Products that appear in several categories
- Printer-friendly versions, and content republished on other sites
How to use canonical tags
- Give every indexable page a self-referencing canonical tag with its full, absolute URL.
- Point duplicates to the main version, which must be indexable and return a 200 status code.
- Keep signals consistent: internal links, sitemaps and hreflang tags should use the canonical URL.
- Don’t point to a page with different content; use a redirect or noindex for that.
A canonical tag is a strong hint, not a command: Google may pick a different canonical if other signals disagree. The URL Inspection tool in Google Search Console shows which URL Google chose.
Canonical tag, redirect or noindex?
| Situation | Use |
|---|---|
| Two URLs show the same content and both must stay available | Canonical tag on the duplicate pointing to the main URL |
| An old URL has been replaced for good | A 301 redirect. See 301 redirects |
| A page should not appear in search at all | A noindex tag (and leave it crawlable so Google can see the tag) |
Other ways to set a canonical
Besides the tag in the page head, you can send a Link: rel="canonical" HTTP header, which helps for PDFs and other non-HTML files, or list only canonical URLs in your sitemap. Use one clear method and keep the signals consistent.
Common canonical mistakes
- Canonical tags that point to a redirected, blocked or noindexed page.
- Pointing every page to the home page.
- Different canonical tags in the HTML and in the rendered page after scripts run.
- Canonicalizing pages whose content really differs.
- Using both noindex and a canonical to another page on the same URL.
Canonical URL FAQs
Does Google always follow the canonical tag?
No. It is a strong hint. Google may choose another URL if redirects, links and sitemaps point elsewhere.
Do I need a canonical tag on every page?
A self-referencing canonical on each indexable page is a common good practice, and it protects against tracking parameters.
How do I see which canonical Google chose?
Use the URL Inspection tool in Search Console.