February 18, 2013. Difficulty rose by +11.47% to 3.65M from 3.28M.
Change
+11.47%
New difficulty
3.65M
Period length
12.6 days
Network hashrate then (7-day)
—
Bitcoin price then
$27
Hashprice then
—
The 2,016 blocks before it took 12.6 days instead of 14, so the network had more hashrate than the difficulty assumed, and difficulty rose by 11.47%: 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.