Ethereum Classic vs Ethereum
One chain reversed a hack and moved to proof-of-stake. The other refused and kept mining. Nine years on they share an address format, which is where the money actually gets lost.
Short answer: they were the same chain until July 2016. Ethereum forked to reverse a hack; Ethereum Classic is the chain that did not. Ethereum has since moved to proof-of-stake and carries almost all of the activity. Ethereum Classic is still mined, has a capped supply, and has been reorganised by 51% attacks more than once.
And the practical warning first, because it is the part that costs money: ETC and ETH addresses are identical in format. Sending one to the other's address looks completely valid and is not recoverable by us or by any exchange.
What happened in 2016
The DAO was an investment fund written as a smart contract on Ethereum, and it held a very large share of all the ether in existence. In June 2016 an attacker exploited a reentrancy bug and began draining it.
The response split the community into two positions that were both coherent.
One said the point of a blockchain is that it cannot be rewritten, and that a chain which reverses transactions when enough important people are unhappy is not doing the job it exists for. Code is law, including when the code is wrong.
The other said the fund was a large fraction of the whole network, the theft was unambiguous, and refusing to act out of principle would kill the project in its infancy.
The second position won the vote. In July 2016 the chain forked and the drained funds were returned. The chain carrying that reversal is what everyone now calls Ethereum. The unmodified chain, where those transactions still stand, continued as Ethereum Classic.
Everything before block 1,920,000 is shared history. Everything after is two separate ledgers.
What is different now
Consensus. Ethereum moved to proof-of-stake in September 2022 — validators stake ETH, blocks arrive on a fixed twelve-second schedule, and mining ended. Ethereum Classic kept proof-of-work and is still mined, with blocks roughly every thirteen seconds. It absorbed a good deal of GPU mining capacity when Ethereum stopped needing it.
Supply. Ether has no hard cap, though issuance is low and EIP-1559 burns a portion of every fee, so supply can shrink in busy periods. Ethereum Classic adopted a capped emission schedule with a ceiling around 210.7 million ETC, reducing rewards at fixed intervals. Whether a cap matters is a question about what you think money is; it is a real difference either way.
Security budget, and this one is not symmetric. Ethereum Classic's hash rate is a small fraction of what secures Bitcoin, and in January 2019 and again across August 2020 it was subject to 51% attacks that reorganised the chain and enabled double spends. That is not a reputational point, it is a specific and repeated event, and it is why exchanges require far more confirmations for ETC than they do for chains of comparable block time. For an ordinary swap it matters little; for a large transfer it is the reason to wait.
Ecosystem. Substantially all of the stablecoins, applications, tokens and liquidity live on Ethereum. Ethereum Classic runs the same virtual machine and can execute the same contracts, but almost nothing chose to deploy there.
The address problem
Both chains use the same 42-character 0x format, and the same private key controls the same address on both. That combination is the trap: an ETC transfer to an address you copied from an Ethereum wallet is a valid transaction to an address you do control — but on the wrong chain, and the coins are only recoverable if you can import that key into a wallet pointed at Ethereum Classic. If the address came from an exchange, you generally cannot, because you never held the key.
The same hazard covers every other EVM network — BNB Smart Chain, Polygon, Arbitrum, Base, Avalanche's C-Chain — all sharing the format with each other and with both of these. Checking the format is not enough; the receiving wallet has to be on the chain you are sending to. The general version of this is in what is a wallet address.
Which one is worth holding
That is a question about what you are buying rather than which is better engineered.
Ethereum is a bet on the network everything was built on, now settling under proof-of-stake with an issuance policy that can go negative when the chain is busy. Ethereum Classic is a bet on proof-of-work, a fixed cap, and the principle that a ledger should not be edited — with the honest caveat that a chain's security is bought with hash rate, and this one has been overpowered before.
Neither is a privacy asset. Both ledgers are fully transparent, and an address on either accumulates a permanent public record of every token, contract and counterparty it has touched. If that is the thing you care about, the relevant move is off both of them — see ETH to XMR and is Bitcoin anonymous, which applies to Ethereum in exactly the same way.
The asset pages are here: Ethereum and Ethereum Classic.
Common questions
Is Ethereum Classic the original Ethereum?
Yes, in the literal sense: it is the continuation of the chain as it existed before the 2016 fork, with the DAO transactions intact. Ethereum is the forked chain. The naming runs the other way round to the history because the overwhelming majority of users, developers and exchanges followed the fork.
Why is ETC worth so much less than ETH?
Almost everything that gives Ethereum value — the applications, the stablecoins, the liquidity, the developers — stayed on the forked chain. Ethereum Classic kept the ledger and very little of the ecosystem. The repeated 51% attacks did not help.
Can I send ETH to an Ethereum Classic address?
The transfer will be accepted, because the address is valid on both chains, and the funds will land on whichever chain you actually sent from. Recovering them means controlling the private key on that chain, which you do not if the address belonged to an exchange. Confirm the network before sending, not the format.
Is Ethereum Classic still being attacked?
The known 51% attacks were in 2019 and 2020, and hash rate rose substantially when Ethereum's miners needed somewhere to go after the 2022 merge. The structural point stands regardless: a proof-of-work chain that is not the largest user of its algorithm can be rented against, which is why extra confirmations are standard for ETC.
Does Ethereum Classic have smart contracts?
Yes — it runs the same virtual machine, so Ethereum contracts can be deployed to it largely unchanged. The difference is that hardly anyone has, so there is little to interact with.
Which is better for swapping?
Ethereum, by a wide margin of liquidity — it is quoted by more of our partners against more assets, which usually means a better rate. ETC is quotable too; expect a wider spread and more confirmations before the payout leaves.
