Bitcoin has no company and no CEO, yet it has upgraded many times. Forks are how. Here is what soft and hard forks are, who decides, and what miners actually do.
By Michal Beno, CEO, OneMiners30 October 2026
A fork is a change to the rules that Bitcoin software follows. A soft fork makes the rules stricter, so old software still accepts the new blocks and the network stays as one chain. A hard fork loosens or breaks the old rules, so old software rejects the new blocks, and if not everyone upgrades, the chain splits in two. Bitcoin upgrades by soft fork, as with SegWit in 2017 and Taproot in 2021. Splits such as Bitcoin Cash in 2017 created separate coins.
2,016
blocks in one signalling window
95%
BIP 9 threshold to lock in
90%
Speedy Trial threshold, Taproot
709,632
block where Taproot activated
BIP 9 and Bitcoin Core 0.21.1 release notes (1 May 2021); Bitcoin Optech, Taproot topic, November 2021.
KEY TAKEAWAYS
First, what are the rules?
Bitcoin runs on thousands of computers called nodes. Each node keeps a full copy of the ledger and checks every new block against a fixed list of rules: blocks must not be too large, signatures must be valid, no coin may be spent twice, and the miner may pay itself only the allowed reward, today 3.125 BTC plus fees. A block that breaks any rule is rejected, no matter how much work went into it.
This is the key to understanding forks. There is no central server to update. If the rules are to change, the people running nodes must choose to run software with the new rules. A fork is simply what happens when some nodes follow one set of rules and some follow another, and the chain can branch like a fork in a road.
Soft fork vs hard fork, in plain English
Think of a club with a dress code. A soft fork is like changing the rule from "wear shoes" to "wear black shoes". Anyone checking the old rule still lets black-shoe wearers in, so old and new members stay in the same room. A hard fork is like changing the rule to "sandals allowed". Old doormen turn sandal-wearers away, and the club can split into two rooms.
Soft fork vs hard fork at a glance
OneMiners summary, October 2026, based on the BIP process at github.com/bitcoin/bips.
Why does a soft fork need most of the hashrate? If only a few miners enforce the stricter rule, the rest could build a longer chain containing blocks the new rule forbids, and upgraded nodes would refuse to follow it. When a large majority of hashrate enforces the new rule, any block that breaks it is quickly orphaned, and everyone stays on one chain. That is why miners are asked to signal first.
How miners signal: BIP 9 explained
Every Bitcoin block has a header with a small version field. Under BIP 9, written in 2015, that field is treated as a row of switches, and each proposed upgrade gets its own bit. A miner that is ready for the upgrade sets the bit to 1 in the blocks it produces. Nodes count those bits in fixed windows of 2,016 blocks, about two weeks, the same length as a difficulty period.
THE SIGNALLING THRESHOLD
BIP 9 lock-in: 1,916 of 2,016 blocks = 95%
Speedy Trial (Taproot): 1,815 of 2,016 blocks = 90%
BIP 91 (2017): 269 of 336 blocks = 80%
Defined
The upgrade is written into node software with a bit number, a start date and a timeout date.
Started
From the start date, miners can set the bit in their blocks to show they are ready.
Locked in
If enough blocks in one 2,016-block window signal, the upgrade is locked in. There is no going back.
Active
After one more window, nodes begin enforcing the new rules on every block.
Failed
If the timeout passes without lock-in, the deployment fails and can be tried again later.
In practice, the hardware does not vote. A Bitcoin miner such as an Antminer S21 hashes whatever block template its mining pool gives it. The pool operator chooses the version bits, so when people say miners signalled, they usually mean pools did.
2017: SegWit and the Bitcoin Cash split
Segregated Witness, or SegWit (BIP 141), moved signature data into a separate part of each transaction. That fixed a long-standing bug called transaction malleability and let blocks carry more transactions without raising the old 1 MB limit for old nodes. Signalling opened on 15 November 2016 with the 95% BIP 9 threshold.
It stalled. As Bitcoin Magazine reported in May 2017, support sat around 30% of hashrate for months, as some large miners held out for a bigger block size instead. Users answered with BIP 148, a user-activated soft fork (UASF): from 1 August 2017, nodes running it would reject any block that did not signal for SegWit. Miners then adopted BIP 91, which needed only 80% over a short 336-block window and made SegWit signalling mandatory. It locked in during July 2017.
Signalling: thresholds vs what happened
Share of blocks signalling, percent
Sources: BIP 9, BIP 91 and Bitcoin Core 0.21.1 release notes; SegWit support near 30%: Bitcoin Magazine, May 2017; lock-in window blocks 477,792 to 479,807, August 2017.
On 1 August 2017, at block 478,558, a group that wanted bigger blocks instead of SegWit launched Bitcoin Cash, a hard fork with a larger block size limit. Everyone holding bitcoin at that block also held the same amount of BCH. Bitcoin itself carried on: SegWit locked in on 9 August and activated at block 481,824 on 24 August 2017.
2021: Taproot and Speedy Trial
Taproot (BIPs 340, 341 and 342) added Schnorr signatures and a new way to write spending conditions, making complex transactions smaller, cheaper and more private. After the long SegWit fight, developers debated how to activate it. One camp wanted BIP 8 with lockinontimeout (LOT) set to true, which forces signalling in the last window so the upgrade locks in by a deadline, whatever miners do.
The compromise was Speedy Trial, shipped in Bitcoin Core 0.21.1 on 1 May 2021: a short window of about three months, starting after 24 April 2021, with a 90% threshold. The 1,815th signalling block arrived at block 687,284 on 12 June 2021, and the upgrade locked in. To give everyone time to update, activation was set for block 709,632, reached on 14 November 2021, about 260,406 blocks before today's height.
How long each soft fork took
Days from the signalling start date to activation
OneMiners calculation from deployment dates in BIP 68, BIP 141 and the Bitcoin Core 0.21.1 release notes. Taproot locked in after 49 days but waited for a fixed activation height; SegWit locked in after 267 days.
Ways to activate a soft fork
Sources: BIPs 8, 9, 91 and 148 at github.com/bitcoin/bips; Bitcoin Core 0.21.1 release notes, 1 May 2021.
So who really decides: miners or nodes?
Both matter, in different ways. Miners produce blocks and make a soft fork safe by enforcing the new rules with their hashrate. Full nodes, run by exchanges, businesses and individual users, decide which blocks are valid. A miner that breaks the rules those nodes enforce simply wastes electricity: its blocks are rejected and its reward never becomes spendable bitcoin.
Who does what in a Bitcoin upgrade
OneMiners summary, October 2026. 2017 showed the balance: miners stalled SegWit, but nodes and the economy pushed it through.
Hard-fork coins: Bitcoin Cash, Bitcoin Gold and BTCB2
A hard fork that splits the chain creates a new coin with a shared history. Holders at the split block own coins on both chains. Whether the new coin has lasting value depends on whether miners, exchanges and users support it.
Major Bitcoin forks, with dates
Sources: block explorers (blockchain.com), BIPs 16, 68 and 141, Bitcoin Optech (Taproot, November 2021), OneMiners BTCB2 explainer (16 September 2026). Soft-fork dates are activation dates.
Bitcoin Gold (24 October 2017) switched to the Equihash algorithm so it could be mined on graphics cards instead of SHA-256 ASICs. Bitcoin SV split from Bitcoin Cash on 15 November 2018, a fork of a fork. Most recently, BTCB2 split from Bitcoin on 8 August 2026 and replaced SHA-256 with BLAKE2b, so a Bitcoin miner cannot mine it at all. OneMiners explains the details in What is BTCB2?.
Where SHA-256 hashrate went at the BTCB2 split
Share of SHA-256 hashrate, 8 August 2026
The lesson for Bitcoin miners: SHA-256 hashrate overwhelmingly stays where the economic value is, on Bitcoin.
What forks mean for someone running a Bitcoin miner
For a hosted miner, a soft fork is mostly invisible. The pool updates its node software and block templates, and the machines keep hashing. An Antminer S21 earns about $7.96 a day at today's numbers before and after an upgrade, because the block reward and difficulty do not change with a soft fork.
What matters is a pool that keeps its software current. Hardware firmware is a separate matter, covered in the OneMiners manuals and firmware library.
Antminer S21 200T$907Hashrate200 TH/sEfficiency17.60 J/THPower draw3,520 WBreak-even power$0.094/kWhNet/day at 4.80c$3.90View on OneMiners
Antminer S21 XP Hyd 473T$6,199Hashrate473 TH/sEfficiency12.00 J/THPower draw5,676 WBreak-even power$0.138/kWhNet/day at 4.80c$12.29View on OneMiners
Antminer S23 Hyd 580T$12,299Hashrate580 TH/sEfficiency9.50 J/THPower draw5,510 WBreak-even power$0.175/kWhNet/day at 4.80c$16.74View on OneMiners
SHA-256 Bitcoin miners hash on whichever chain their pool points to. Live OneMiners prices, 6 October 2026; net per day at $0.048 per kWh, at today's numbers, before pool fees.
Bitcoin's fork history is a story of slow, careful change. Soft forks like SegWit and Taproot improved Bitcoin without splitting it, and hard-fork coins came and went while SHA-256 hashrate stayed on the main chain. For miners, that stability is the point: the rules that pay for security change rarely and only with broad agreement. OneMiners hosts efficient Bitcoin miners from $0.048 per kWh, and from $0.0364 on a 7-year prepaid contract. See how it works or the hosting locations.
Frequently asked questions
What is the difference between a soft fork and a hard fork?
A soft fork makes the rules stricter, so old nodes still accept new blocks. A hard fork changes the rules so old nodes reject new blocks, which can split the chain.
Do miners decide Bitcoin upgrades?
Not alone. Miners signal and enforce soft forks with their hashrate, but full nodes decide which blocks are valid. In 2017, nodes and users pushed SegWit through after miner signalling stalled.
Did Taproot create a new coin?
No. Taproot was a soft fork. It activated at block 709,632 on 14 November 2021 without splitting the chain.
If Bitcoin hard forks, do I get the new coin?
Usually, holders at the split block own the same amount on both chains, as with Bitcoin Cash in 2017. Whether exchanges list it and what it is worth are separate questions.
Can a Bitcoin miner mine a fork coin?
Only if the fork keeps SHA-256, as Bitcoin Cash does. Forks that change the algorithm, such as Bitcoin Gold or BTCB2, cannot be mined with a Bitcoin ASIC.
Mine on the chain that matters: efficient Bitcoin miners, hosted from $0.048 per kWh.
Browse Bitcoin minersSee hosting locationsSOURCES AND DATA
- BIP 9, Version bits with timeout and delay (created 4 October 2015): 95% threshold, 1,916 of 2,016 blocks; states and bit scheme
- BIP 141 (SegWit) deployment: start 15 November 2016, timeout 15 November 2017; BIP 68 (CSV) deployment: start 1 May 2016
- BIP 91: 269 of 336 blocks (80%), bit 4; BIP 148 UASF from 1 August 2017; BIP 8 lockinontimeout: github.com/bitcoin/bips
- SegWit signalling near 30%: Bitcoin Magazine, BIP 148 and BIP 149, May 2017
- SegWit lock-in 9 August 2017 and activation at block 481,824 on 24 August 2017; Bitcoin Cash at block 478,558, 1 August 2017; Bitcoin Gold at block 491,407, 24 October 2017: blockchain.com explorer
- Bitcoin SV split from Bitcoin Cash, 15 November 2018: Electron Cash, November 2018 hard fork notice
- Taproot Speedy Trial, 90% threshold, start 24 April 2021, minimum activation height 709,632: Bitcoin Core 0.21.1 release notes, 1 May 2021
- Taproot lock-in at block 687,284 on 12 June 2021 (F2Pool) and activation at 709,632: Bitcoin Optech Taproot topic and newsletters, June and November 2021
- BTCB2 split at block 961,632 on 8 August 2026, 97 to 98% of SHA-256 hashrate stayed: OneMiners, What Is BTCB2?, 16 September 2026
- Block height, subsidy and hashprice: mempool.space and CoinGecko, 5 October 2026; miner prices: OneMiners catalogue, 6 October 2026
- Hosting rates: published OneMiners location pages
Michal Beno
CEO of OneMiners, the global Bitcoin mining hosting and hardware platform with 15 published hosting locations, 7-year fixed electricity contracts and a 7-year hardware warranty. He writes about the economics of industrial Bitcoin mining.
Informational only, not financial advice. Figures are a snapshot from public market data and news reports as of 5 October 2026 and can change quickly. Crypto prices can fall as well as rise. No return is offered or implied. Do your own research.
