301 redirects pass full link juice

It is claimed that 301 redirects do not leak link juice and are recommended fixes for many a problem.

301 redirects are not harmless, they leak valuable link juice both Bing and Google have confirmed this. How much do the leak? Matt Cutts has said a little bit.

How much is a little bit?

The most common figure that SEO’s quote is 10% some say as little as 5% some say 15%. The 15% figure has some logic behind it, at least for Google. The original Google algorithm released long ago, showed that all link requests only passed 85% of PageRank, this is so they do not get into infinite loops, its called decay. PageRank is calculated many times to get a correct answer, the amount of decay has an affect on how many times you need to calculate, so it would make sense to have all requests decay at the same rate.

When to use a 301 redirect

You should only use a 301 redirect when the only other alternative is worse. They should not be used willy nilly. You should not use 301 redirects to correct any sort of internal linking and therefore create un-necessary redirects, you should always point internal links to the final destination.

You should never use chains of 301 redirects, Google will follow a few of them but leak each time, Bing will only pass link juice though a single redirect.