Bitcoin Difficulty Jumps 5.92% as Hashrate Reclaims 1 Zettahash

Bitcoin's mining difficulty rose 5.92% on Friday, from 132.72 trillion to 140.58 trillion. Bitcoin.com News, filing at 20:30 UTC on 16 October, puts the retarget at block 971,712 and calls it the third-largest increase of the year and the network's highest difficulty reading since 5 March. Difficulty is the number the protocol resets every 2,016 blocks to hold the average block near ten minutes, and it tracks computing power up and down. Power came back. Total hashrate crossed 1,000 exahash per second again, which is one zettahash, and Friday's adjustment is the protocol taking the slack out.

Machines switched on while revenue cooled

Hashprice, the daily revenue a single petahash per second of computing power is expected to earn, sat at $36.75 on Friday. A month earlier, on 16 September, it was $37.56. It went above $41 twice in between, once on 2 October, and for much of that month ran 6% to 9% above the September level. Bitcoin.com reads the hashrate recovery off that better revenue. CryptoTicker, writing three days before the retarget, reads it the other way: miners switched hardware on over the two weeks to Friday even though the price had been giving ground since the start of October, which it treats as the ordinary pattern after a hardware delivery. Neither account addresses the other. The count itself is not in dispute — Bitcoin.com has the network at 1,024.96 EH/s with block times around 8 minutes 45 seconds, against a September reading when hashrate was down more than 20% and operators were moving capacity into AI work.

The estimate and the number

CryptoTicker modelled the adjustment at about 5.5% on 13 October, with the retarget expected near 13:59 UTC on Friday. At that point 438 of the epoch's 2,016 blocks were still outstanding and blocks were arriving every 9.49 minutes against the ten-minute target. The realised figure came in at 5.92%, above the model, and the piece had said plainly that its estimate moves with the speed of the blocks still to come. The previous adjustment, on 3 October, was minus 0.03%. That figure appears in one account only.

What the retarget costs a miner

The block subsidy does not move with difficulty. It is fixed at 3.125 BTC plus fees, so what changes is how many competitors chase the same reward. CryptoTicker's worked example uses a 5.49% rise and has a miner with unchanged hardware keeping 94.80% of its previous share, revenue per terahash down 5.20%, and the electricity bill where it was. On the 5.92% actually recorded the reciprocal is nearer 94.4%, which is arithmetic on CryptoTicker's method rather than a figure any outlet published. The squeeze is sharp at the company level and slight at the market level: the network mints roughly 450 BTC a day from the subsidy, and CryptoTicker put a full day's output at about 0.12% of bitcoin's 24-hour turnover. Operators who cannot cover the bill sell coins or switch machines off, and the hashrate forward market is where that risk is priced before it arrives.

The next retarget has two dates

Bitcoin.com puts the following adjustment on or around 28 October with an early estimate of plus 14.24%, noting that only a few dozen of the 2,016 blocks had been mined when it published. CoinWarz's dashboard, read on Saturday afternoon, gives 29 October and about 151.22 trillion, a rise of 7.57%. They do not reconcile. Both are projections from different samples of block speed taken at different moments, and neither states a cut-off against the other. If the new epoch runs fast, difficulty climbs again and the pressure lands on the operators who just plugged machines in; if that October fleet goes quiet, the adjustment after it comes out the other way.