https://github.com/hartmanm How difficulty adjustment works: Every 2016 blocks, the Network adjusts the current difficulty to estimated difficulty in an attempt to keep the block generation time at 10 minutes or 600 seconds. Thus the Network re-targets the difficulty at a total difficulty time of:  2016 blocks * 10 minutes per block = 20160 minutes / 60 minutes = 336 hours / 24 hours = 14 days. When the Network hashrate is increasing; a difficulty ( 2016 blocks ) should take less than 14 days.  How much less can be estimated by comparing the % Network hashrate growth + what the Network hashrate was at the beginning of the difficulty ( 2016 blocks ) against what the Network hashrate was at the beginning of the difficulty ( 2016 blocks ).  This is only an estimate because you cannot account for "luck"; but you can calculate reasonably well using explicitly delimited stochastic ranges. The easy way to think about this is to look at this graph and see how close to 0 the current data points are on its y axis.  If the blue line is above 0 the difficulty ( 2016 ) blocks should take less than 14 days; if it is below it should take more. http://bitcoin.sipa.be/growth-10k.png