Before jumping to this question directly, let’s get an idea of what meta-description is and what is its function.
A meta description is a snippet that gives a brief information about a page’s content. It is a tag in HTML underneath the blue clickable links taking you to the page you requested for…
…They are between one sentences to a short paragraph which Google shows you in the search results when the queries you searched for are contained in the description (in an attempt to better answer your query).
The meta-description is an HTML tag. The main function of a meta-description is to get a visitor from Google to click that particular link. In other words, meta-descriptions are there to generate clickthroughs from the search engines. There is an indirect benefit of these meta-descriptions.
Google uses click-through-rate (CTR) as a way of determining if that page is a good result…
…To serve its purpose, a meta-description has to be appealing and inviting. It should contain a quality description of the product or the information contained in the link.
As for the link is used, it ranks up higher on the list shown by the search engine for the purpose of a rich description or the better idea of the product. The snippet seemed to be crossing 155 characters back in the past years which seemed to be very rare but it is time to revisit these guidelines on the meta-description heading into 2018.
Digging in, the average reaches up to 215 character length for meta-descriptions. This is quite interesting as it leaves the limit way behind. On the other hand, some snippets are way too short because their meta-descriptions are very short.
But the question is – Do we really care about the very long or too short meta-descriptions? The answer is NO. But what we really want to know is why Google cuts off the long snippets down to the character limit. On more digging, we find that the average character limit after the cut off remains up to 200 to 212 long.
According to the new limit of 300 to 325 characters, the cutoff percent is out 33%. As there is no such thing as the right amount of characters, the meta-descriptions are cut-off unevenly.
We’ve got a closer spike in 300 to 325 character range but the descriptions are cut off in the 200 character range. We later found out that these are two things going on.
Firstly, the video snippets reduce the character size to 200. These snippets seem to be maxed out in 2 lines and are further restricted by the space that the video thumbnail occupies. Space remaining for the snippet is about 70%.
Secondly, the pre-cut meta-tags seem to reduce the character limit.
The long meta-descriptions are pre-truncated. So, most probably, the meta-description length is decided by Google as there might be add-ons by Google in the snippet or there might be some information that Google itself might want to add in the given meta-descriptions.
The question is- does Google rewrite all the snippets? Studies told that 35% snippets had no change, 15% had some added data. The rest 50% of snippet perfectly matched the data. Cutting it short, we can say that 300 characters are a pretty safe bet for meta-descriptions.