Unlock the Hidden Power of Meta Descriptions: The Secret Weapon to Skyrocket Your Website Traffic
In these instances, the meta description that users see may be more than 300 characters. This makes it difficult to confidently say how long they should be.
So what should you do? As a best practice, stick with the 150-character guideline (but be aware that this isn’t a firm rule).
It’s nice to actually see how meta descriptions will appear in search results before you publish a page. Fortunately, there are plenty of free tools you can use to preview them. Here are a few:

Ready to get serious about writing meta tags? They aren’t difficult to write, but there are some tips and general best practices you can follow to make sure you get them right.