Difficulty by halving epoch since 2009. It rose in every epoch, and the current one is up +68% since April 2024.
Data from mempool.space, refreshed hourly.
Mining difficulty sets how much work the network requires to find a valid block. Every 2,016 blocks, roughly every two weeks, the protocol compares how long those blocks took against a target of 10 minutes each. If blocks came in faster, difficulty rises. If they came in slower, it falls.
A difficulty of 1 equals about 4.3 billion hashes (2³²) per block on average. Today's difficulty of 148 trillion means the network needs about 637 sextillion hashes to find one block. The chart plots that number on a log scale, because it has grown by trillions of times since the first block in 2009.
Each halving cuts the block subsidy in half and starts a new epoch on the chart. Difficulty has risen in every epoch so far. The percentage gain shrinks over time because each epoch starts from a much larger base.
| Epoch | Years | Starting difficulty | Ending difficulty | Growth |
|---|---|---|---|---|
| Epoch 1 | 2009–2012 | 1 | 3.44 million | +343,890,796% |
| Epoch 2 | 2012–2016 | 3.37 million | 213 billion | +6,331,871% |
| Epoch 3 | 2016–2020 | 213 billion | 16.1 trillion | +7,444% |
| Epoch 4 | 2020–2024 | 15.14 trillion | 86.39 trillion | +471% |
| Epoch 5 (current) | 2024–2028 | 88.1 trillion | 148 trillion so far | +68% |
Difficulty is the denominator in every miner's revenue. A machine earns block rewards in proportion to its share of the network's hashrate, so when difficulty rises 6%, the same machine produces roughly 6% less Bitcoin per day. Revenue per terahash, known as hashprice, falls whenever difficulty climbs faster than the Bitcoin price.
That is why efficiency and power cost decide which machines stay profitable over an epoch. Run the numbers for a specific miner with the Bitcoin mining calculator, or compare the two lines directly on the Bitcoin price vs mining difficulty chart.
Bitcoin mining difficulty is 148 trillion (148,364,561,003,867), set at the adjustment on Oct 29, 2026. The next adjustment is estimated at -3.16% around Nov 13, 2026, 978 blocks from now.
Every 2,016 blocks, which works out to about every two weeks. The adjustment aims for an average of one block every 10 minutes, and a single change can move difficulty by no more than a factor of four in either direction.
Difficulty follows hashrate. When more machines, or more efficient ones, come online, blocks arrive faster than every 10 minutes and the next adjustment raises difficulty to slow them back down. It falls when hashrate leaves the network, as it did in July 2021 after mining moved out of China.
A miner earns block rewards in proportion to its share of total hashrate, so higher difficulty means each terahash earns less Bitcoin. A 6% difficulty increase cuts a machine's daily Bitcoin output by roughly 6% unless the Bitcoin price rises to offset it. That is why efficiency, measured in joules per terahash, and power cost decide which machines stay profitable.
The period between two Bitcoin halvings, about four years or 210,000 blocks. The halvings fell in November 2012, July 2016, May 2020 and April 2024, and the next is expected around April 2028. This chart measures how much difficulty grew within each epoch.
