Why pixels, not characters
Google cuts titles at about 600 pixels and descriptions at about 920 pixels on desktop, not at a fixed number of characters. A title full of wide letters like W and M gets cut sooner than one with narrow letters. This tool measures each line in pixels with Arial, the font Google uses.
How to use it
Paste titles one per line, or paste or upload a CSV with a header row. Columns named Title, Meta Description and Address (or URL) are picked up automatically, so exports from Screaming Frog, Sitebulb, Shopify and most CMSs work as they are. Problems are listed first, and you can download all results as a CSV.