As with many areas of the search engine world, there are some grey areas but Google does provides some guidelines on how to manage redirections and what each communicates to the search engine. This is a guide to using canonical tags vs 301 redirect.
A 301 Redirect signals to the search engine that the page has been moved permanently, remove the page from the index and pass any acquired SEO credit to the new page.
Meanwhile, a Canonical Attribute signals to the search engine that the document has multiple versions of the page (or its content). The URL pointed listed in the canonical attribute should be consider the original, the real page: only it should be indexed. The duplicated pages will be kept on the website but should not be indexed by the search engine.
What is a Canonical Tag?
A canonical tag (sometimes referred to as rel=canonical or a canonical link) is an HTML element that indicates that a provided URL is the primary source of information.
The tag also tells search engines that the primary page is the only page (relevant to that topic) that should rank on search engine result pages. This prevents indexing duplicate content on multiple pages.
The canonical tag was introduced in 2009 by Google, Yahoo, and Bing to reduce duplicate URLs on sites.
This group effort between major search engines made it clear that a canonical tag would be the best option to help clean up sites and clearly indicate the preferred version of content largely duplicated across multiple URLs.
Benefits SEO gets from Canonical Tags
Canonical tags aren’t a direct ranking signal; however, they do provide clarification for search engines that can have a positive effect.
Because they indicate the preferred version of nearly-identical content on multiple pages, it leaves no doubt for search engines which page to index. This can lead to increased rankings for the preferred page as the backlinks and other factors are passed to the canonical page.
Implementing a Canonical Tag in Your Pages
The canonical tag is inserted in the <head> section of a webpage. When you add the rel canonical tag, it should always point to the new/updated page. The code looks like this:
<link rel=”canonical” href=”http://example.com/primary-page”/>
It’s that simple!
Just implement the code in the head section (usually near the title tag and meta description), be sure that it points to the page you want to be indexed, and search engines will take it from there.
In WordPress, adding a canonical tag is simpler. You just have to paste the URL on the “ADVANCED” section in the SEO plugin section of the page.
When to Use a Canonical Tag Over a 301 Redirect
As mentioned above, a canonical tag is best used when you have similar or exact same content across multiple pages. However, you may be asking yourself, “A 301 redirect solves that same problem, though. Which do I choose?”
The answer isn’t always obvious. Here are three common examples that you may be experiencing:
Example 1: New Version of Old Content
If you operate a long-running blog, you may have old articles that have been re-written or updated on another page with a new URL.
Not only does the previous blog have outdated information, but you also don’t want these two pages to compete for the same traffic. Because these old URLs serve no unique purpose, these older pages do not need to exist at all.
In this example, a 301 redirect would be the recommended option.
Example 2: Similar Product Pages
If you have an eCommerce site with a lot of products, you may have several pages with similar merchandise (i.e. a gray shirt with logo vs. a red shirt with a logo). If you want Google and other search engines to only index the most predominant of these products but still want users to have the option to see and shop both color variations, a canonical tag is an ideal choice.
Let’s break this down a bit further.
In this example, we have two products, a gray shirt, and a redshirt. The URLs look like this:
Let’s also assume that we’ve determined that black leather shoes is the primary version of the two products.
That means we’ll need to implement the canonical tag in the <head> section of the brown leather shoe page.
Example 3: A Product/Page No Longer Exists
If you’ve discontinued a product or page, or if you’ve migrated your site from HTTP to HTTPS a 301 redirect is almost always the best option.
Because the old pages either don’t exist or, in the case of a secure site transition, they are exactly the same as the new URLs, there is no benefit to keeping them accessible.
Real-World Problems with Canonical Tags
The examples above are common areas where questions about canonical arise, but real life is rarely so organized.
If you find yourself in a situation that wasn’t explained above, ask yourself this question: “Does the old page offer any unique value to the user?”
If the answer is, “Yes. It is still valuable to users,” then a canonical tag is most likely your best bet.
If the answer is, “No. It has no value to users,” then a 301 redirect may be preferred.
The 301 HTTP status code has always been the standard for managing the complete and permanent redirection of a page. By implementing this command you will eventually pass the majority of the original page’s link authority, relevance and ranking power to the page you are redirecting to. Google’s Distinguished Engineer Matt Cutts has said, you’ll lose “just a tiny little bit, not very much at all” which “doesn’t change over time”.
The 301 tells both users and search engines that your original page is no longer relevant and that the most relevant and up to date information can be found on your new page.
Sounds simple enough, right?
Real Word Problems with 301
There are a few possible problems with implementing a 301 redirect.
First, it might not be possible for you to implement HTTP status codes. Maybe you don’t have FTP access, or perhaps your web designers have told you it isn’t possible. Either way, without server-side access, a 301 simply isn’t an option.
Another possible downside of the 301 is that it does sometimes take a while for the search engines to attribute your new page with the search authority of your original page. This all depends on how often your site, and the original page, is crawled by the search engines. This delay means that a 301 is something you should never rely on for short term or last-minute campaigns.
Finally, the most common problem is the 301 being used incorrectly. It’s surprisingly common to see marketers develop a completely new site and then use a 301 to point all the pages of the original website to new site’s homepage. This isn’t what the 301 is intended for. This approach undermines the relevancy of any search traffic and could result in a very high bounce rate. It’s a lose/lose situation and unfortunately, this is just one example among many.
Don’t let these issues put you off. A 301 redirect is still the clear choice for permanent page redirection in most cases.
When to Use 301
- As default – this is the preferred method
- Pages that are being permanently moved or replaced
- Domains that are permanently moved (acquisitions, rebranding, etc.)
- 404 pages and expired content (assuming relevant content or a page exists)
Final Thoughts on Implementing Redirect 301 and Canonical Tags
Redirect options can be intimidating, but hopefully, now you have greater clarity on the best course of action. Both options will pass a similar amount of link juice, and will be treated similarly by Google. But in general, the 301 redirect is the preferred route.