Google have updated the way they show your title snippet in the Search Engine Result Pages, calculating based on pixel width rather than number of characters. This makes a lot of sense, as with many fonts including Arial, characters are different widths, particularly when using capital letters; however it does make it hard for Webmasters to have control over their search snippets without thorough planning.
Google calculate the pixel width of the characters used in titles with a limit of 512 pixels, truncating anything over this limit with the use of an ellipsis. They are also now using a larger Arial font at 18px compared to the previous 16px, despite still truncating based on 16px. The upshot of this change is that text is no longer truncated at word boundaries (before or after a word). Google may resolve this so that titles are chopped off at word boundaries as before, rather than in the middle of a word. It’s also worth noting that Google appear to remove non ASCII range characters from the beginning of the text when displaying in the SERP view.
You can read more about the changes and a good way to calculate what your SERP snippet will look like over on Screaming Frog: https://www.screamingfrog.co.uk/page-title-meta-description-lengths-by-pixel-width/
