Why a title that "fits" in an editor can still get cut off in Google
Search result titles and descriptions aren't truncated by a fixed character count — they're truncated by pixel width, because the display is a visual line of text at a set font and size, not a text box with a character limit. That's why two titles with the same character count can behave differently: a title full of narrow letters like "i" and "l" fits more characters into the same visual width than one full of wide letters like "m" and "w". Character counters, including the ones on this site's other tools, are a useful rough guide, but this preview tool goes a step further by measuring the actual rendered pixel width of your title and description using the same font metrics a browser would use, then truncating at the same point a real search result would.
Seeing the preview update as you type also makes it much easier to write a title and description that work together as a single pitch, rather than writing them in isolation and hoping they read well side by side. Because the breadcrumb-style URL line, the blue title, and the description all render together in the same layout search results actually use, you can immediately see whether your URL structure looks clean, whether your title reads naturally at its cut-off point, and whether your description delivers its key point before it's cut off.
Writing for the moment someone is deciding whether to click
A search result snippet is functionally an advertisement for your own page, competing against several other results a searcher is scanning in a few seconds. The title's job is to confirm, at a glance, that this result matches what someone searched for — specific and concrete language usually beats vague, clever phrasing here, since a search results page is not the place to make someone guess what a page is about. The description's job is different: it has more room to make a case for why this particular page is worth clicking over a competing result covering the same topic, whether that's through specificity, a clear benefit, or simply directly answering the exact question implied by the search.
Because both fields are visually truncated with an ellipsis rather than wrapped onto a new line, it's worth writing the most important information first in both the title and the description. A title where the key differentiator sits at the very end is often not worth writing that way at all, since a meaningful share of real searches happen on narrower mobile screens where the same title truncates even earlier than it would on a wide desktop display.
Keep in mind while using this preview
Search engines occasionally rewrite a page's title or description in the actual results page, generating their own summary from the page content when they judge it better matches a specific search query than the meta tags provided. That means this preview shows the snippet you're aiming for and asking to be used, not an absolute guarantee of what every searcher will see for every query. It remains the right starting point, since providing a clear, accurate, well-written title and description is exactly what makes a search engine more likely to use them as written rather than generating a substitute.