user21126: What is the lowest block time of any cryptocurrency? I don't mean the time of an individual block, but the target time per block.
What is the shortest reasonable block interval?

user23123: There was a coin called Flashcoin that tried to do 6-second block times. I don't think that's being actively mined anymore as another Flashcoin appeared a year later (60-second block times).
Ethereum is planning a 12-second block time. Vitalik makes an argument for why that's probably the minimum for now here. Of course, ethereum hasn't been released yet, but Fastcoin with its 12-second block time is probably considered the lowest block generation time currently.

user89690: EOS has blocks that are published every ~500ms, so around two blocks per second. That's a contender for the top spot for sure

21126: <p>What is the lowest block time of any cryptocurrency? I don't mean the time of an individual block, but the target time per block.</p>

<p>What is the shortest reasonable block interval?</p>
 23123: <p>There was a coin called <a href="https://bitcointalk.org/index.php?topic=222450.0" rel="nofollow">Flashcoin</a> that tried to do 6-second block times. I don't think that's being actively mined anymore as another <a href="https://bitcointalk.org/index.php?topic=635403" rel="nofollow">Flashcoin</a> appeared a year later (60-second block times).</p>

<p><a href="http://en.wikipedia.org/wiki/Ethereum" rel="nofollow">Ethereum</a> is planning a 12-second block time. Vitalik makes an argument for why that's probably the minimum for now <a href="https://blog.ethereum.org/2014/07/11/toward-a-12-second-block-time/" rel="nofollow">here</a>. Of course, ethereum hasn't been released yet, but <a href="https://bitcointalk.org/index.php?topic=218852.0" rel="nofollow">Fastcoin</a> with its 12-second block time is probably considered the lowest block generation time currently.</p>
 89690: <p>EOS has blocks that are published every ~500ms, so around two blocks per second. That's a contender for the top spot for sure</p>
