Will using SSL improve my search engine rankings?
We’re sometimes asked if using SSL will improve a site’s search engine rankings.
Google did say in 2014 that SSL is one of the factors they consider for a slight ranking increase. They described it as a “very lightweight” ranking signal that's less important than most other factors, although it should grow over time.
On the other hand, using SSL for every page slows down sites a little bit, which can slightly reduce a site's ranking. So these two factors may offset each other to some extent.
Because sites like Google don’t provide exact details of their algorithms, it’s impossible for anyone to give a better answer than this. However, using SSL probably won’t hurt, and there are security advantages to SSL that are making more sites use it, which is the real reason Google wants to encourage it (and why we do it on many of our own pages). So it’s a reasonable thing to try for other reasons if you’re modifying your site.