Google Giving You Until April 21 to be Mobile Friendly

Beginning April 21, Google will begin using mobile friendliness as a ranking signal. That means sites that aren’t mobile friendly will be pushed down the search results page, if not penalized more severely.

Google has a page where you can test your site to see if it’s mobile friendly. There’s also a Google guide to making your site mobile friendly.

Your Webmaster Tools account also will give you a full list of mobile usability issues.