Google truncates by pixels, not characters
Nearly every "meta description length" guide gives a character count — 155, 160, 920. Those numbers are averages of something Google does not measure. Google renders the snippet in a container of fixed pixel width and cuts whatever overflows.
The practical consequence: a title made of narrow letters like "Illinois Litigation Timeline" fits comfortably, while "Wow: Mammoth Marketing Machines" of the same character count gets cut. This tool measures approximate rendered width per character, which is why the character counts it reports vary between two titles that both "fit".
The measurement here is an approximation of Google's font metrics, not a pixel-perfect reproduction. Treat the boundary as a guideline with a small margin, not a hard line.
Google rewrites titles anyway — so why bother?
Google has rewritten displayed titles for years, and by its own account changes them for a substantial share of results. It pulls from your H1, from anchor text, from on-page headings — whatever it judges more useful for the query.
That is an argument for writing better titles, not for ignoring them. Google's own guidance is that rewrites usually happen when a title is too long, keyword-stuffed, boilerplate across the site, or missing. A concise, descriptive, page-specific title is the one most likely to survive intact.
Meta descriptions are rewritten even more often, because Google frequently assembles a snippet from the passage matching the query. They still matter: when yours is used, it is the sales pitch that decides the click.
Writing the title tag
Put the distinguishing information first. Mobile truncates hardest, and a title that opens with your brand name spends its most valuable pixels on something the reader already knows from the URL.
The reliable pattern is Primary topic — qualifier | Brand, with the brand last so it is the part that gets cut. Every page needs its own title: duplicate titles across a site are one of the strongest triggers for Google replacing them.
Writing the meta description
The description is not a ranking factor — Google confirmed this a long time ago — but it is a click-through factor, and click-through is what actually moves traffic. Treat it as ad copy for a free ad slot.
Say what the page delivers and why it is worth opening, in plain language. Include the terms someone would search, because matching words are bolded in the result and draw the eye. Avoid the generic opener ("In this article we will discuss…") that wastes the first third of the space.