The Los Angeles Times has a great story that tells us…
I’ve wondered about that 160 character limit but never thought to learn why that number was chose (as opposed to something like 255 for example). The article explains how Friedhelm Hillebrand (working for German Telecom) decided upon the number after some informal tests of simply typing a bunch of sample sentences.
The article also explains that Twitter’s 140 character limit comes from SMS text messaging’s 160 character limit. Twitter reserves 20 characters for a unique user address and leaves the rest (140) for the tweet.
As always, you can find me on Twitter at: @toddogasawara