When the same content sits at more than one URL, search engines have to guess which one to rank. The canonical tag removes the guesswork by naming your preferred version. Get it wrong and you can split ranking signals or point Google at the wrong page entirely. Here is how to read yours and confirm it is correct.
What rel=canonical does
A canonical tag lives in the page <head> and points to the URL you want indexed:
<link rel="canonical" href="https://example.com/page/" />
It tells search engines: of all the URLs showing this content, treat this one as the original. Duplicate or near-duplicate pages then pass their ranking signals to the canonical URL instead of competing with it. This matters anywhere the same content appears at multiple addresses: tracking parameters, print versions, paginated archives, or HTTP and HTTPS variants.
A self-referencing canonical is a page pointing to its own URL. That is normal and recommended for standalone pages, since it locks in the exact preferred address. A cross-domain canonical points to a URL on a different domain, used when you syndicate content and want the original site to get the credit.
Common mistakes
- Pointing to the wrong URL. A templated tag that hardcodes one page across the whole site funnels every page to a single canonical. Always confirm the href matches the page you are on.
- http vs https. A canonical on an HTTPS page that still references
http://sends Google to the insecure version. Match the protocol exactly. - Missing or extra trailing slash.
/pageand/page/are different URLs to a crawler. The canonical must match the form your site actually serves. - No canonical at all. Without one, search engines pick a version for you, and it may not be the one you want.
How to check it
The Canonical Tag Checker inspects HTML you paste. It does not fetch URLs, so you view the source first, then paste it in.
- Open the page in your browser and view its source (right click, then “View page source”, or
Ctrl+U). - Copy the full HTML.
- Paste it into the Canonical Tag Checker.
- Read the result: it pulls the canonical href so you can confirm it matches the page, uses HTTPS, and has the right trailing slash.
Because everything runs in your browser, the HTML you paste never leaves your device.
Related tools
- Confirming the page can actually be indexed? Try the Indexability Checker.
- Checking the title and description that show in results? Use the Google SERP Preview.
- Listing your canonical URLs for submission? See the XML Sitemap Generator.
One correct canonical per page keeps your ranking signals where they belong.