Google Updates its Stance on 301 Redirects and Link Juice
Using 301 permanent redirects has been a long-running standard best practice for forwarding an old, outdated URL to a new one. However, this got a bit muddied when the “rel=canonical” link tag was created in order to help search engines determine which page on a website was the authoritative and correct page.
In a recent question on Google engineer Matt Cutt’s blog, he was asked what is better to use, a 301 redirect or a rel=canonical tag in order to retain link juice.
According to Cutts, using a 301 redirect for a URL does lose some of the link juice from the originating URL, but it’s such a small amount that it’s negligible, and it doesn’t increase over time. Even though the rel=canonical tag has its uses (if you don’t have access to a server-based ht-access file you would need to make a 301 redirect) Cutts says that 301 redirects should always be preferred over rel=canonical tags whenever possible due to their wide support and better implementation across browsers.