How often does Bitcoin's mining difficulty adjust?

Bitcoin’s mining difficulty adjusts every 2016 blocks. That target is designed to make the network produce blocks at an average rate of one every 10 minutes, so 2016 blocks represent roughly two weeks of mining.

The protocol compares the actual time needed to mine the previous adjustment period with the expected two-week interval. If miners collectively found blocks faster than intended, difficulty rises; if they were slower, difficulty falls. This automatic feedback system helps keep new bitcoin issuance and transaction confirmation timing relatively predictable even as mining hardware and network hash power change.

A common mix-up is confusing 2016 blocks with Bitcoin’s 210,000-block subsidy-halving interval. Difficulty adjustments happen about every two weeks, while halvings reduce the block subsidy roughly every four years. The adjustment is also not a promise that every individual block takes exactly 10 minutes: blocks arrive randomly, and the ten-minute figure is a long-run average.