Our Bitcoin difficulty adjustment chart shows the percentage change of Bitcoin’s difficulty for each epoch.
These epochs refer to the roughly two week periods between difficulty adjustments. Every 2,016 blocks, the Bitcoin network evaluates the prior epoch’s average block time; if the average is below the 10 minute targeted average, the Bitcoin network raises its difficulty to ensure consistent block times and rate of issuance. Vice versa, if Bitcoin’s block times were slower than 10 minutes on average, the Bitcoin network will decrease the difficulty to speed up block finds.
Bitcoin miners must pay attention to these swings in Bitcoin network difficulty because they affect the BTC denominated rewards they earn in exchange for their hashrate.