Canonical tags: fix duplicate content the right way
A canonical tag tells Google which address is the main copy of a page. Learn when to use it, how to add it, and how to fix missing, wrong and duplicate canonicals.
By the WebTools team · Published 2026-11-10 · 1 min read
The same page can often be reached at several addresses: with tracking parameters, sorting options, print versions or both http and https. Search engines then have to guess which one to rank. A canonical tag tells them.
How to add it
Put a link element with rel="canonical" in the page head, with the full preferred address of the page. Most SEO plugins (Yoast, Rank Math) and shop platforms add a self-referencing canonical automatically.
When to point elsewhere
- Duplicate content: two pages with the same text, such as a product in two categories. Point both at the main one.
- Filter and sort URLs: point them to the unfiltered category.
- Syndicated articles: the copy can point to the original.
Common mistakes
- Every page points to the homepage: a theme bug that tells Google to ignore all your other pages.
- Canonical to a redirected or 404 page.
- http:// canonicals on an https:// site (see HTTPS redirects).
- Canonical and noindex together: mixed signals. Choose one.
Duplicate content
If two pages truly have the same content, the best fix is to merge them and 301-redirect the weaker one. Use the canonical when both must stay. The full SEO audit finds pages with identical text, pages without a canonical, and canonicals that point to another page, so you can check each one is intentional.
Questions about this topic
Should a page have a canonical pointing to itself?
Yes, a self-referencing canonical is good practice. It protects the page from copies created by tracking parameters and filters.
Is a canonical tag the same as a redirect?
No. A redirect sends visitors to another page. A canonical is a hint to search engines only; visitors still see the page they opened.
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