Bitcoin's mining difficulty saw its last adjustment in 2025, with forecasts indicating a rise in January 2026. The Bitcoin network's mining difficulty, which reflects the computational challenge of adding a new block to the blockchain, has been a key indicator of network health and miner activity throughout the year.
Throughout 2025, Bitcoin mining experienced substantial growth and volatility. Data indicated a 35% increase in Bitcoin mining difficulty over the year, climbing from 109.8 trillion hashes to 148.2 trillion. This increase directly correlated with the expansion of the network's computing power, as the 7-day average hashrate rose from 795.7 TH/s to 1,070.3 TH/s, peaking at 1,151.6 TH/s in October. The network hashrate, representing the total computational power contributed by miners, highlights the increased resources dedicated to securing the blockchain.
The year 2025 was marked by Bitcoin's mining sector reaching zettahash scale, transforming network security. Starting the year at approximately 801 exahashes per second (EH/s), the network achieved a milestone in September by exceeding one full zettahash per second (ZH/s). This indicated that the network was performing 10²¹ SHA-256 calculations every second, demonstrating a significant increase in computing power compared to previous years.
The Bitcoin network's difficulty reached a new peak after an adjustment on October 29, 2025, at block height 921,312. The difficulty level increased by 6.31%, reaching an all-time high of 155.97 trillion. The average hash rate of the Bitcoin network then rose to 1.13 zettahashes per second (ZH/s).
Despite the overall growth in mining difficulty and hashrate, miners faced challenges including fluctuating prices and increasing operating costs. Bitcoin's price experienced volatility, consolidating around $87,300 after briefly surpassing $89,000. A winter storm in early 2025 also caused power outages for some operations, leading to a slight decrease in difficulty. Even with these challenges, the network's computing power remained resilient.
The increase in mining difficulty reflects the automatic adjustments the Bitcoin network makes to maintain a consistent block time of approximately 10 minutes. As more miners join the network and increase the overall hashrate, the difficulty adjusts upwards to ensure that blocks are not mined too quickly. Conversely, if miners leave the network, the difficulty adjusts downwards. This mechanism is crucial for maintaining the stability and security of the Bitcoin blockchain.
The last difficulty adjustment in 2025 resulted in the difficulty settling at 148.2 trillion hashes. While there had been a slight decrease from the all-time high in October, the overall trend for the year showed a substantial increase. As the year closes, the Bitcoin network is expected to adjust upwards again in January 2026.
