Mining difficulty

To produce a block, miners must find a hash below a target number. Difficulty expresses how small that target is: the lower the target, the more attempts are needed on average. Bitcoin recalculates it every 2,016 blocks, roughly two weeks, aiming for one block every ten minutes. If blocks came faster than that, difficulty rises; if slower, it falls.

Because difficulty follows hashrate, it is a common gauge of mining competition, and news often reports new records. When China banned mining in 2021 and much hashrate went offline, Bitcoin posted its largest downward adjustment, close to 28%. Rising difficulty means each machine earns fewer coins.

Adjustments are capped and only happen at set intervals, so sudden hashrate drops can slow blocks for days. For miners, difficulty is a key cost input alongside power prices and the halving, and it tends to keep climbing as more efficient hardware arrives.