What should the character limit be on microblogging?

Evan Prodromou who I finally met at FOSDEM recently, has been running a poll to find out whats the best character limit for microblogging.

For our flagship site, Identi.ca, which runs on the status.net cloud service and uses the 0.9.0 beta, we’d like to open up the discussion of what an appropriate character limit should be. Setting a site-wide limit is a community decision we’d like to leave in the community’s hands. In a conversation on Identi.ca we’ve solicited some candidate character limits that we’d like people to decide on.

• 140 is compatible with Twitter; in many languages a notice with 140 characters fits into a single SMS message*
• 280 can fit into two Twitter or SMS messages
• 300 is a fan favorite
• 420 is Facebook’s status limit and 3 Twitter tweets or SMS messages
• 500 is a little bigger
• 1000 is bigger than that
• Unlimited
• Other

So personally I think 300 is enough. 300 will hold a very long URI with room for query string values. Also having it about the size of two text messages seems about right. If you stick to ANSI only characters you usually get about 306 characters to text with (160+160 with overhead) on most phones. Unicode drops it down to 280 characters which still seems fairly close to 300. I’m also thinking 300 characters keeps things micro readable still.

The idea of a more structured microblogging with URIs as metadata in interesting but I think metadata should be inline and in plain view. Its one of the neat things about Microblogging, which would be a shame to remove. Also got to say anything more complex than the current microblogging setup would maybe cause too many problems with backwards compatible. Literate results are good, if you want metadata use blogging instead.