December 21, 2013. Difficulty rose by +30.01% to 1.18B from 908.35M.
Change
+30.01%
New difficulty
1.18B
Period length
10.8 days
Network hashrate then (7-day)
0.0 EH/s
Bitcoin price then
$614
Hashprice then
$286,662/PH/day
The 2,016 blocks before it took 10.8 days instead of 14, so the network had more hashrate than the difficulty assumed, and difficulty rose by 30.01%: one of the largest adjustments on record. For every machine on the network that is a pay cut of the same size until the next retarget.