One key aspect of SEO, often overlooked but essential, is the proper utilization of the rel=canonical tag. This tag is a powerful tool that aids webmasters in steering search engines towards the right page version and preventing duplicate content issues.

By comprehending and employing the rel=canonical tag efficiently, you can amplify your website’s performance, streamline search engine crawling, and make sure that the right content reaches your audience. This guide is tailored to provide you with practical insights into the role of rel=canonical, its benefits, and how to use it in various scenarios.

In this guide, we’ll dive into the ins and outs of rel=canonical, providing you with practical examples and scenarios to help you apply it to your website like a pro.

What is rel=canonical?

Before we dive into the complexities, let’s begin with the basics. The rel=canonical tag is a HTML attribute that website owners can use to prevent duplicate content issues. It does this by specifying the “canonical” or “preferred” version of a web page. Simply put, it tells search engines which version of a page they should index and rank, providing a solution to multiple URLs containing similar or identical content.

For example, if you have product pages on your e-commerce website with the same description but different color options, you can use rel=canonical to point search engines to a single, preferred version.

Where are canonical tags added?

Canonical links are added to the HEAD section of HTML pages and indicate which URL should be considered the authoritative source for that particular page. By adding this tag, web admins can ensure that their content is indexed correctly and that visitors will be directed to the desired version of their webpage.

How does canonical work

Here is an example to help you better understand how canonicals function. Consider operating a cheese website with several categories for white, blue, cheese spread, etc. Additionally, you have developed pages for several nations’ cheese, such as South African cheese, French cheese, and Italian cheese.

Additionally, your URL structure reflects this. If we have a South African red wine, it might be offered at these two URLs:

Search engines correctly identify this as duplicate content because both URLs display the same cheese. We include the canonical identifiers shown below if the first URL is our preferred URL:

<link rel="canonical" href="">

By doing this, we instruct Google always to use that URL. Google often complies with this directive. Thus, this resolves your duplicate content issue.

Benefits of Using Canonical Tags

Using canonical tags helps consolidate link equity from all duplicate pages into one main page. This makes it easier for search engines to crawl and index your content, helps with crawl budget efficiency, and helps prevent any negative SEO impacts caused by multiple URLs containing similar content.

The biggest advantage of using canonical links is that it boosts SEO, increase traffic flow, and improves the reliability of data collected from analytics tools. It also provides a way for web admins to specify their preferred domain so that all incoming links are directed to the correct page version.

Additionally, canonical tags help resolve issues with similar or duplicate content on your site by telling search engines which page should be indexed and returned in search results. This ensures that users are always taken to the most relevant and up-to-date version of a page when searching online.

Why Use rel=canonical?

The significance of rel=canonical in SEO cannot be overstated. Here are a few reasons why:

Prevents Duplicate Content Issues

Duplicate content can confuse search engines, making it hard for them to determine which version of the content to index or rank. By indicating the canonical URL, you can guide search engines to the version you prefer, eliminating confusion.

When multiple pages with similar content exist, the link equity (the value passed from one page to another via hyperlinks) can be diluted. The rel=canonical tag helps consolidate this equity on your preferred page, enhancing its ranking potential.

Saves Crawl Budget

Search engines allocate a certain amount of resources, or “crawl budget,” to crawl your site. If they waste time crawling multiple similar pages, they may not get to your unique content. The rel=canonical tag helps search engines focus their efforts more effectively.

What is the difference between a canonical URL and a redirect?

Canonical URLs and redirects are somewhat similar in instructing the search engine to index page B rather than page A.

But there is a significant difference: site users and search engine crawlers cannot access page A with a redirect. The user and the crawler are not rerouted when using a canonical. Page A is still displayed to users.

When to use a redirect?

If you don’t want page A to be accessible, use a 301 redirect from page A to page B. This might have happened because you altered the URL or combined pages A and C into page B. You should then direct bots and visitors to page B in that situation.

When to use a canonical URL?

Sometimes you prefer an alternative URL indexed than a page available. Canonicals are the solution to the situation. Pagination is a fantastic example because you want users to be able to move between the pages, but you don’t want each of them to be indexed separately.

Let’s get into the details.

When to use canonical URLs?


Pagination is used to separate product pages and blog category pages into separate lists.

This creates a lot of different pages, but we don’t want pages 1,2, 3 to 100 indexed by search engines as different pages.

This is where canonical URLs come in: create a page with all the posts without pagination (for instance, on /blog), and set that page as a canonical URL or all paginated pages. Example:

<link rel="canonical" href="">

Don’t make the canonical URL the first page of a paginated list because it is far more difficult to index articles or products not on page 1.


Frequently, filters are applied as URL parameters on product category pages. The URL is updated as you utilize the filters on the website.

You’ve seen pages like:

Each of the URL variations can be indexed by Google even without the use of canonical URLs:

And so on…

The danger is clear: these URLs may compete for the same keywords. Again, the solution is easy. When a canonical URL is added without any URL parameters, only that one will be indexed by search engines:

<link rel="canonical" href="">

Very similar pages

Several websites feature pages that are quite similar but differ just a little. The identical garment might be sold in a clothes store in white, blue, and red, each with its URL. The same can be done for various sizes, tastes, and so forth.


Depending on the search intent, you should canonicalize such pages or not. Do you anticipate people searching for particular sizes, tastes, or colors? Each page needs to be indexed separately to provide searchers with the results they want. If not, it would be wise to canonicalize the pages to one of the alternatives.

Products or posts in multiple categories

You can add goods or posts to several categories in some content management systems. The same page could appear under several URLs if that category is also included in the URL.

Once more, canonicalization aids in correction. To prevent duplicating content, set up a canonical that leads to the most appropriate category.

Content distribution

Canonical URLs can point to distinct domains. That’s particularly helpful if you’ve authored a guest post published on your website and another publisher.

Here is an example of Yahoo using the same content from Reuters and Business Insider. While they don’t provide canonical to the source (bad practice), if you are a publisher, you would want to reference the original site URL:

This would be considered duplicate content if there were no canonical URLs. Google may believe one of the two articles was plagiarized. You may avoid penalties and ensure that your site receives the SEO benefits by setting a canonical URL that points to your page. Of course, whether you can include a canonical URL depends on the publication.

By default: self-referencing canonical

A canonical doesn’t need to link to another page. A canonical that references the page itself is known as a self-referencing canonical.

It is always advised to include a self-referencing canonical on every page if it doesn’t have a canonical pointing somewhere else.

Should I add a self-referencing canonical?

If I don’t use URL parameters or pagination on this page, do I still need a self-referencing canonical?

The answer is yes: external sites may link to that page and add their parameters even though you cannot utilize URL parameters. Including a canonical URL that directs users to the page can stop the parameterized URL from being preferred over the original URL.

Common issues with canonical URLs

Search engines adhere very closely to canonical URLs. That implies that it’s a strong instrument but also that you should use caution. There are a few problems we frequently encounter:

Pointing to a non-indexable page

The goal of the canonical URL is for search engines to index that page. The page won’t be indexed if it has a no-index header or tag, nor will any pages that use that non-indexable page’s canonical URL.

Pointing to a non-indexable page

Therefore, ensure the canonical URL you’re using can be indexed at all times. The canonical report from SiteGuru provides this for you.

Canonicalizing All Pages to the Homepage

This is a common mistake where all pages of a website are set to point to the homepage as the canonical URL. This can lead to search engines ignoring your canonical tags altogether, as they could interpret this setup as an error.

Multiple rel=canonical tags

Having more than one rel=canonical tag on a page confuses search engine bots and is considered an error.

Having too many rel=canonical tags could confuse search engine bots and lead them astray when trying to index your site correctly in the SERPs. The best practice here is only to include one “self-referencing” tag per page pointing back at the root URL of the page.

Redirected canonical

You might redirect pages to other pages as your website expands and changes. Indexation issues may arise if a redirected page is designated as the canonical URL on various pages. Google tries to use the canonical URL you supply, but it typically ignores redirected pages.

Redirected canonical

Avoid redirects and always use the final URL as the canonical URL.

Don’t set a canonical tag to a redirected page: Google states that they usually respect the canonical URL you set, but not always. That’s because canonical tags are hints, not directives, so they might ignore them if they detect other signals pointing to another version of the same page.

Duplicate canonical

Assume that the canonical URL for page 2 is set to be page 1. However, page 2 also has a page 3 canonical URL. That isn’t very productive.

Duplicate canonical

Instead, the canonical URL for page 2 should be page 3. Doing this increases the likelihood that search engines will correctly understand your canonicals and save the crawl budget.

Using relative URLs

Don’t ever use relative URLs for canonicals. Include the path (/blog/article), the protocol (HTTPS://), and the complete domain name (

Absolute URLs provide more information than relative ones, but they can also cause confusion among search engine bots and lead to incorrect indexing or ranking of pages on your website. To avoid this issue, always use relative URLs when implementing rel=canonical tags on your site instead of absolute ones.


You should be aware that canonical URLs are case-sensitive. You can use uppercase or lowercase letters if you utilize consistent capitalization on all pages. 

(note the uppercase P) is a different page than

Use lowercase URLs everywhere: in your URL routing, links, and canonical URLs.

Automated tools may make mistakes

Many content management systems (CMS) and eCommerce platforms support automated canonical tag implementation – but this doesn’t mean that it’s always correct or up-to-date with changes made on your website! Web admins should regularly check their implementations to ensure accuracy and avoid potential issues with duplicate content in SERPs (Search Engine Results Pages).

Sitemaps and canonical URLs

Sitemaps aid in indexing your website by search engines. You shouldn’t include any pages in your sitemap with canonical URLs linking to other pages because those sites won’t be indexed.

Canonical URLs for non-HTML content

HTML pages make it simple to set a link rel=” canonical” href=””>. But what if you want to include a canonical URL in a downloadable document? That HTML code cannot be included in an Excel or PDF document. You can still specify a canonical URL on a non-HTML document by using HTTP headers. A canonical header would appear as follows:

Link: <>; rel=”canonical”


Understanding and implementing the rel=canonical tag effectively can make a significant difference to your SEO efforts. By properly using this simple line of code, you can guide search engines to your preferred content, avoid duplicate content issues, and ensure that your website is indexed and ranked accurately.

So, if you haven’t yet tapped into the power of the rel=canonical tag, it’s high time you did. And remember, SEO is a journey, not a destination. With the right tools and strategies, including the rel=canonical tag, you can successfully navigate your way to the top of the search engine results.

Remember, SEO isn’t about tricking search engines – it’s about working with them. And the rel=canonical tag is one of the best ways to do just that.