Bitcoin Universe · Model 05
The difficulty engine
Bitcoin brings blocks back toward about ten minutes on average after mining power joins or leaves, with a lag of up to one period. It does so with a slow governor: once every 2016 blocks, never in between.
Time acceleration
Mechanism 1 of 6
Network hash rate
Readout
Adjustments
| Period | Took | Ratio to 14 days | Old difficulty | New difficulty |
|---|
new target = old target × clamp(actual, 302,400 s, 4,838,400 s) ÷ 1,209,600 s; “actual” spans 2015 intervals (first to last block of the period). Values are rounded to compact precision as nodes do.
Expected interval, block tokens, the period carriage and the new difficulty
The old difficulty and the last observed gap
Simulated hash rate and block arrivals
The retarget rule is Bitcoin's mainnet consensus rule. The hash rate, the starting difficulty and every block arrival are simulated (seeded, exponentially distributed gaps) and time is accelerated. The expected interval is an average; the observed gaps scatter widely around it.