What would happen if 90% of the Bitcoin miners were to suddenly stop mining Bitcoin, i.e. the Bitcoin network's hashing power would drop to 10% of the previous amount.

Would it become more difficult for the rest of miners to mine? Would transactions take longer than usual?

  • I'm not sure this question is actually based on anything - can you provide more information? Apart from the fact that the process of mining transaction blocks will never stop, this seems like an odd premise for a question.
    – T9b
    Commented Feb 17, 2014 at 18:46

1 Answer 1


The probability of 90% of miners suddenly stopping mining bitcoin is only slightly more probable than the chance of the sun going dark this afternoon.

Anyway, supposing that 90% of the active bitcoin miners were to suddenly vanish, the first effect would be that blocks would take much more time to be confirmed (10x longer, so 100 minutes per block instead of 10 on average). The next time the difficulty is adjusted (up to 2016 blocks later), the difficulty would be reduced such that blocks again take about 10 minutes to confirm depending on the new speed of the network as a whole. The difficulty is normally adjusted so that 2016 blocks is about two weeks, but if you just lost 90% of your hashing power then the next adjustment could be up to twenty weeks later.

The last time the difficulty was 10x less than it is now was around October 2013. You can see the difficulty history here .

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  • 2
    "up to 2 weeks later" is incorrect - it is "up to 2016 blocks" (1007 on average), which is approximately 2 weeks; however, if 90% of the miners leave, it will be 10 times that, "up to 20 weeks later" Commented Feb 17, 2014 at 20:44
  • @AMADANONInc.: good point, I'll update. Commented Feb 17, 2014 at 20:46
  • 1
    I would like to note that in such a dramatic loss of interest of miners the coin could easily be considered dead, but even so there is no need to wait up to 20 weeks: crowd, still retaining faith could modify easily available sources, compile and agree on a new version of cliet/protocol which will lessen either the difficulty right away, or the remaining numbers of blocks to next difficulty adjustment. This is possible, i believe, due to bitcoin being a network of consensus. I am unable to speculate on consequences of such intervention for the blockchain, though.
    – zoigo
    Commented Jan 20, 2015 at 12:36

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