The major Bitcoin forks are specific historical events where the Bitcoin blockchain was permanently divided into separate networks with their own coins, rules, and communities. Bitcoin Cash (BCH) forked on August 1, 2017 at block 478,558 over block-size disagreements; Bitcoin SV (BSV) split from BCH on November 15, 2018 over governance; Bitcoin Gold (BTG) forked on October 24, 2017 to change the mining algorithm; and SegWit2x was canceled in November 2017 after failing to achieve broad consensus despite majority miner signaling.
Which forks actually created new coins?
This article covers the contested hard forks that produced lasting chain splits. For the general mechanics of how forks work at the protocol level, what soft forks and hard forks mean technically, and how activation proceeds, see Bitcoin forks explained. Here the focus is on what happened in each specific case, why it happened, and what changed for holders.
Not every proposed fork succeeded. Failed proposals like Bitcoin XT, Bitcoin Classic, and Bitcoin Unlimited never gained enough support to produce lasting chains. SegWit2x was canceled before activation. The forks that persisted are the ones where both sides had enough mining, exchange listings, and user demand to sustain two independent chains.
Bitcoin Cash: The August 2017 block-size split
Bitcoin Cash forked from Bitcoin at block 478,558 on August 1, 2017 at 13:16 UTC. The last shared block was mined by BTC.com. Every holder of BTC at that block height received an equal amount of BCH on the new chain (source: Wikipedia).
The rule change: Maximum block size increased from 1 MB (with SegWit's 4 MW effective limit) to 8 MB. Later BCH upgrades raised this to 32 MB (May 2018) and beyond.
Why it happened: The scaling debate that had consumed the Bitcoin community since 2015 reached a breaking point. One faction, including mining operator Bitmain, wanted larger blocks for more on-chain transactions. The other faction, including most Bitcoin Core developers, preferred keeping blocks small to preserve node decentralization and scaling via Lightning Network and SegWit.
Who was behind it: Bitmain (Jihan Wu), Bitcoin ABC development team (Amaury Sechet), Roger Ver, and miners representing a significant minority of SHA-256 network hashrate.
What holders experienced:
Anyone controlling private keys at the snapshot received 1:1 BCH
Exchanges like Coinbase credited BCH to users who held BTC at the fork block
BCH implemented replay protection via a modified SigHash algorithm, preventing cross-chain transaction replay
Transaction fees on BCH dropped significantly, often under $0.01 compared to BTC peaks above $20 during late 2017 congestion
Current state (April 2026): BCH trades around $448 with a market cap around $8.9 billion. It maintains active development. The upcoming "Layla" upgrade on May 15, 2026 will add smart contract capabilities via the Loops and Functions CHIP (source: CoinGecko). BCH remains far smaller than BTC by market cap, hashrate, and adoption.
Bitcoin SV: The November 2018 split from BCH
Bitcoin SV forked from Bitcoin Cash on November 15, 2018 at BCH block 556,766. This was a fork of a fork: BSV split from BCH, not from BTC directly (source: Wikipedia).
The rule change: Block size increased dramatically. BSV launched with 128 MB blocks and later removed the cap entirely, pursuing what its proponents called "unbounded scaling."
Why it happened: A governance dispute within the Bitcoin Cash community. Craig Wright (who claims to be Satoshi Nakamoto) and Calvin Ayre's CoinGeek mining operation pushed for restoring what they termed the "original Bitcoin protocol" with no block size cap. The Bitcoin ABC team (led by Amaury Sechet) wanted to add new opcodes and maintain a more conservative upgrade path.
The hash war: Both sides competed for hashpower in November 2018. CoinGeek and associated pools initially directed substantial mining at BSV. The split was acrimonious, with each side claiming legitimacy as the "real" Bitcoin Cash. Markets settled it: BCH retained the ticker on most exchanges; BSV traded under a new ticker.
What holders experienced:
BCH holders at the fork block received 1:1 BSV
Several exchanges paused BCH trading during the hash war due to uncertainty
Replay protection was implemented after the split, though the initial days carried replay risk
Current state: BSV has seen declining exchange support and trading volume since 2020. Multiple major exchanges delisted BSV following controversy around Craig Wright's legal actions. Development continues under nChain but adoption remains limited compared to both BTC and BCH.
Bitcoin Gold: The mining-algorithm fork
Bitcoin Gold forked from Bitcoin at block 491,407 on October 24, 2017. Unlike BCH and BSV, the dispute was not about block size but about mining centralization (source: Wikipedia).
The rule change: Mining algorithm switched from SHA-256 to Equihash, designed to be GPU-mineable and resistant to ASIC hardware. This made the fork incompatible with all existing Bitcoin mining infrastructure.
Why it happened: At the time of the fork, a small number of ASIC manufacturers (primarily Bitmain) dominated Bitcoin mining hardware production. BTG's founders argued this created centralization risk. By switching to Equihash, they aimed to allow anyone with a consumer GPU to mine profitably.
Controversy: BTG included a "premine" of 100,000 BTG (0.48% of supply at fork): 80,000 for an endowment fund and 20,000 for the development team. This drew criticism from parts of the community that viewed it as a profit extraction.
The 51% attacks: BTG suffered its most significant failure in May 2018 when an attacker gained majority hashrate and double-spent approximately $18 million worth of BTG against exchanges (source: GitHub). A second attack occurred in January 2020. The lower total hashrate of a GPU-mined chain made 51% attacks economically feasible in a way they are not against Bitcoin's SHA-256 network. This demonstrated a core tradeoff: ASIC resistance makes mining more accessible but also makes attacks cheaper. For background on what a 51% attack involves, the dedicated guide explains the mechanics.
Current state: BTG has limited exchange support. Bittrex listed and later delisted it. The ASIC-resistance goal proved difficult to maintain as specialized hardware eventually emerged for Equihash variants. BTG switched to Equihash-BTG after the 2018 attacks.
SegWit2x: The fork that was canceled
SegWit2x was not a successful fork. It was a two-phase proposal: first activate SegWit as a soft fork, then increase the base block size to 2 MB via a hard fork. Only phase 1 succeeded (source: Wikipedia).
The New York Agreement (May 2017): At Consensus 2017, a group of businesses and miners representing over 80% of hashrate signed an agreement to support both phases. Signatories included Digital Currency Group, Coinbase, Bitmain, Blockchain.com, and over 50 other companies (source: Bitcoin Wiki).
Phase 1 succeeded: SegWit activated on August 24, 2017 at block 481,824 as a backward-compatible soft fork. No chain split occurred.
Phase 2 failed: On November 8, 2017, the SegWit2x developers announced cancellation of the 2 MB hard fork, originally planned for block 494,784 around November 16, 2017. The reason: lack of consensus beyond the mining community. Key opposition came from:
Bitcoin Core developers who were not consulted on the agreement
Node operators running User Activated Soft Fork (UASF) clients
Businesses that withdrew support (F2Pool, Bitwala, others)
Community members who objected to the lack of replay protection in the proposal
The lesson: SegWit2x demonstrated that hashpower signaling does not equal network consensus. Over 90% of miners signaled support, yet the fork was canceled because node operators, developers, users, and businesses collectively rejected it. Running a full node and choosing which software to validate is the mechanism by which Bitcoin's rules are ultimately determined, not mining votes.
What happened to supporters: Some attempted to proceed with the fork on November 17, 2017. A bug caused the chain to split one block early at block 494,782 instead of 494,784. The B2X chain quickly died with near-zero hashrate and no exchange support.
Comparing the major forks
Fork | Date | Block height | Rule change | Replay protection | Outcome |
|---|---|---|---|---|---|
Bitcoin Cash (BCH) | Aug 1, 2017 | 478,558 | Block size 1 MB to 8 MB | Yes (SigHash) | Persistent chain, trades actively |
Bitcoin Gold (BTG) | Oct 24, 2017 | 491,407 | SHA-256 to Equihash | Yes (SigHashForkId) | Persistent but declining, 51% attacked |
SegWit2x (B2X) | Canceled Nov 8, 2017 | N/A (planned 494,784) | 2 MB base block | No (major criticism) | Canceled; brief zombie chain died |
Bitcoin SV (BSV) | Nov 15, 2018 | BCH 556,766 | 128 MB+ blocks | Yes (post-split) | Persistent but delisted from many exchanges |
What the forks revealed about Bitcoin governance
The 2017-2018 fork period tested every assumption about how Bitcoin's rules change. Several findings emerged:
Hashpower is necessary but not sufficient. SegWit2x had over 90% miner signaling and still failed. Bitcoin Cash attracted significant mining but never overtook BTC in sustained hashrate or market value. The network follows the rules that nodes enforce, not the rules miners prefer.
Exchange listings determine economic viability. A fork chain without exchange support has no price discovery, which means miners have no revenue incentive. BCH survived partly because major exchanges listed it within days. BSV's gradual delisting from exchanges like Binance and Kraken preceded its decline.
Replay protection is non-negotiable for user safety. SegWit2x's lack of replay protection was a primary reason for its rejection. Without it, every user transaction risked being copied to the other chain. BCH, BSV, and BTG all implemented replay protection, which is why safe transaction handling was possible across chains.
Premines and developer funds create trust issues. BTG's 100,000-coin premine drew criticism. Transparent funding mechanisms matter for community trust in fork projects.
From watching these events unfold at the exchange operations level, the fork period taught us that deposit and withdrawal pauses are the rational response to consensus uncertainty. When you operate infrastructure that handles customer deposits, the risk of crediting the wrong chain or losing funds to replay attacks means caution overrides speed. Most reputable exchanges paused BCH and BTG deposits until replay protection was confirmed working in production.
What holders should do during future forks
For guidance on how forks affect your hot vs cold wallet, how to handle seed phrase security during fork events, and how to avoid common scams that appear around splits, the practical safety steps are:
Confirm replay protection exists before transacting on either chain. If there is no replay protection, do not move coins until the community develops splitting tools.
Control your own keys. Exchange custody means you depend on their policy for fork coin credits. Self-custody wallets give you access to both chains automatically.
Wait for dust to settle. Legitimate fork coins do not expire. BCH was still claimable months and years after the August 2017 split.
Never enter your seed phrase into unknown software. Every major fork spawns phishing sites claiming to "help you claim" coins. Use only official project wallets from verified repositories.
Verify using a block explorer to confirm balances on both chains before attempting any split transactions.
Frequently asked questions about major Bitcoin forks
Which Bitcoin fork created the most valuable new coin?
Bitcoin Cash (BCH) reached approximately $4,300 in December 2017, briefly placing it among the top three cryptocurrencies by market cap. As of end-April 2026, BCH trades around $448 with a market cap near $8.9 billion, making it the most economically significant Bitcoin fork by a wide margin. Bitcoin Gold and Bitcoin SV have substantially lower market caps and trading volumes.
Did SegWit2x fail because miners didn't support it?
The opposite. Over 90% of miners signaled support for SegWit2x via the New York Agreement. It failed because the broader Bitcoin community, including node operators, developers, businesses, and users, rejected the hard-fork phase. This proved that mining power alone does not determine Bitcoin's consensus rules. The network follows whatever rules full nodes enforce, and enough node operators refused the 2 MB hard fork to render it unviable.
Can a Bitcoin fork steal my existing BTC?
No. A hard fork cannot remove coins from your wallet on the original chain. Your BTC remains on the Bitcoin Bitcoin blockchain regardless of what happens on fork chains. The risk is replay attacks, where a transaction you sign on one chain gets copied to the other. Forks with replay protection (BCH, BTG, BSV) prevent this. The original Bitcoin chain itself is never modified by a fork event.
Why did Bitcoin Gold get 51% attacked but Bitcoin did not?
The cost of a 51% attack is proportional to the network's total hashrate and the cost of the hardware required. Bitcoin Gold uses GPU-based mining (Equihash), which means an attacker can rent general-purpose GPU compute from cloud providers. Bitcoin uses SHA-256 ASICs that cost billions in aggregate and have no alternative use. Attacking Bitcoin's ~1 ZH/s network would require acquiring roughly half of all SHA-256 mining hardware globally, an investment measured in billions with multi-year lead times.
Is Bitcoin Cash the "real Bitcoin" as some claim?
Markets, not claims, determine which chain carries the "Bitcoin" designation in practice. BTC maintains the original ticker on every major exchange, the dominant hashrate (over 99% of SHA-256 mining), the highest market cap, and the largest user and developer base. BCH is a separate cryptocurrency that forked over a legitimate scaling disagreement in August 2017. The question is ultimately settled by economic consensus, not by any single party's claim to the name.
Written by the BloFin Academy editorial team. Facts verified against Bitcoin block explorers, Wikipedia fork records, and exchange historical data. Primary sources include BIP-91/BIP-141 activation records, the Bitcoin Cash genesis block at height 478,559, and BTG 51% attack documentation on GitHub.
Disclaimer: This content is for educational purposes only and does not constitute financial, investment, legal, or tax advice. Crypto assets are highly volatile and carry significant risk of loss. Always verify local regulations and consult a qualified professional before making financial decisions.