Hoople - 8:17 pm on Jul 24, 2013 (gmt 0)
There have been title tests of the pixel count to 111 characters, but to me that's way too much! Get it concise without making it into a mini advertorial infomercial!
Google's search downstream partners do clip some of the title and meta-description by 2-4 characters. I tend to use a 68 characters limit for title and 145 characters for meta-description.
By all means test, test and test. Local ISP's search pages, many meta search portals and even AOL clip their data to be shorter. If these pages do NOT matter use your test results to push out the length to what's stated above by aakk9999. This clipping typically takes out the last word - if your last word is longish and goes over the limit by ONE character you loose the whole word (replaced by ...).
This length choice (and the last word[s] clipping) that makes writing naturally sounding ones even more challenging! Some ISP's snag url typos with their DNS and redirect all errors to their search portal. Comcast allows you to opt-out of this....others vary. Some use Google, some Yahoo and a few AOL. Typo a URL to test!
facebook will use 297 characters (of the meta-description) if no Open Graph 'og:description' tag is present.