Ethereum Classic (ETC)

What Ethereum Classic is

Ethereum Classic is the original Ethereum chain, continued without the 2016 hard fork that reversed the DAO hack. Its own site describes it as a "base layer smart contracts platform" that "combines the technology of Ethereum™ (ETH) with the philosophy of Bitcoin (BTC)," secured by proof of work and organized around the principle that a deployed smart contract should run as written (source: ethereumclassic.org, read September 2026).

That principle has a name on the project's own pages: "Code is Law," and the related promise to "Build Unstoppable Applications." Ethereum Classic's site labels these pages "Opinionated Content" that "does not necessarily reflect the view of all ETC stakeholders," which is a useful reminder that the philosophy is a position rather than a technical specification.

Two things distinguish ETC from Ethereum in practice. It has a fixed emission curve with a bounded total supply, and it has committed to remaining on proof of work rather than moving to proof of stake.

For where to buy Ethereum Classic from your country or state, see the availability tables on this page and the venues at Exchanges.

How it works

ETC runs the Ethereum Virtual Machine, so contracts and tooling are broadly familiar to anyone who has worked on Ethereum. What differs is the consensus layer and the money supply.

Blocks are mined. The site states the commitment directly: Ethereum Classic "is committed to remaining on Proof of Work indefinitely in pursuit of decentralization maximalism," and argues that proof of work is "the only one known to provide Sovereign Grade Censorship Resistance." Its stated objections to proof of stake are listed rather than argued in the abstract: "additional complexity, 33% attacks, vulnerability to financial manipulation, centralization of staking custody, the APR arms race, nothing at stake, removal of checks and balances, and the rich get richer."

The mining algorithm was changed by ECIP-1099, known as the Thanos upgrade, to keep consumer hardware viable. Ethash builds a large dataset called a DAG that grows over time, and by epoch 372 that dataset had reached 3.91 GB, pushing 4 GB graphics cards toward obsolescence. ECIP-1099 doubled the epoch length from 30,000 blocks to 60,000, halving the rate at which the DAG grows. The proposal states the effect plainly: activating at epoch 376 "would reduce the DAG size from 3.94GB to 2.47GB," and "with the reduced growth rate, 4GB GPUs will remain supported for an additional 3+ years." The renamed algorithm is Etchash, activated on mainnet at block 11,700,000, epoch 390.

Ethereum Classic also carries an unusual client-level defense against deep chain reorganizations. ECIP-1100 proposes Modified Exponential Subjective Scoring, built on a stated principle: "Small reorgs are normal and healthy; large reorgs are suspicious. Given a reorg of unusual length, nodes should value their local (first-available) segment with preference over the later proposed segment, despite that it may have greater difficulty."

The proposal is careful about its own status. It "falls outside of existing consensus protocol," and a block that fails the test is stored as a side chain rather than rejected, so a segment that later accumulates enough difficulty can still become canonical. Anything under roughly ten minutes is not treated as suspicious. In effect, a node will not silently accept a long, late replacement of history, which is the shape of an attack a chain with modest hash rate has to worry about.

Supply and tokenomics

ETC's monetary policy is set by ECIP-1017 and is stated as a rule rather than a target.

The two supply figures come from the same proposal and bracket the outcome. ECIP-1017 states that "in the worst case scenario (supply wise, which assumes two uncles included every block in perpetuity) the total supply will not exceed 210.7M ETC," and that "should the network remain as efficient… the total supply will not be less than 198.5M ETC." The gap between the two is uncle block rewards, which depend on how often blocks are found near-simultaneously.

The reasoning behind the schedule is stated in the proposal itself. It says the model "provides a balance between providing an acceptable depreciating distribution rate for rewarding high risk investment into the system and maintaining an active supply production over time," and explicitly avoids cutting issuance to zero, describing continued production as a "blow off valve for price increases."

That is the substantive contrast with Ethereum, and the ETC site draws it: "if a project does not have a known future supply, maintainers can arbitrarily inflate the value of a currency away from holders. This risk remains present on all chains that do not have a fixed emissions curve, including Ethereum™."

History

Ethereum Classic and Ethereum were one chain until 2016. The project's own account is direct: "The DAO was a contract that raised a lot of money, but it had a bug that was exploited," and while "70% of the lost funds were recovered… 30% remained in limbo." A hard fork was proposed that confiscated the remaining funds by stopping the attacker's application.

The ETC position is that the fork was not fixing a protocol bug. Its site argues the change "was not fixing a problem with the Ethereum protocol itself, and Ethereum marketed itself on 'Build Unstoppable Applications'," and characterizes the decision process as "a highly questionable 'coin vote'" that "led Ethereum Foundation to support the Hard Fork, breaking their neutrality." It also contends the fork was avoidable, since "the hacked funds could have been recovered on Ethereum Classic, but because of the fork this effort was abandoned."

Whatever one makes of the argument, the outcome is not disputed: the fork split the chain, and the unforked side continued as Ethereum Classic. Its site claims the distinction of being "the longest running Smart Contract Platform."

The upgrades since have served those two commitments. ECIP-1017 fixed the emission curve, ECIP-1099 kept mining accessible on modest hardware, and ECIP-1100 hardened clients against deep reorganizations. None changed the consensus mechanism, which is the point.

Risks and what to watch

Hash rate is therefore the number to watch, and specifically how much of it is rentable. ECIP-1100 mitigates the consequences at the client level; it does not lower the cost of attacking, and by its own admission it "falls outside of existing consensus protocol," so its effectiveness depends on clients implementing it consistently.

Client diversity matters for the same reason. ECIP-1100 warns that inconsistent implementations "might present a risk to network coherence (whether by malicious intention or accident)."

The philosophical commitment cuts both ways. "Code is Law" means a bug in a deployed contract will not be reversed by social consensus. That is the property the chain exists to provide, and it is also a real risk to anyone using an application on it: there is no fork to fall back on.

Ecosystem scale is the practical constraint. ETC shares the Ethereum Virtual Machine, so tooling ports readily, but application activity and developer attention concentrated on the forked chain after 2016.

Frequently asked questions

What is Ethereum Classic's maximum supply?

ECIP-1017 states that total supply "will not exceed 210.7M ETC" in the worst case, which assumes two uncles included in every block indefinitely, and "will not be less than 198.5M ETC" if the network stays efficient.

How does the block reward decline?

Rewards start at 5 ETC in Era 1 and are "reduced at a constant rate of 20% upon entering a new Era," with each era lasting 5,000,000 blocks. Issuance declines toward but never reaches zero.

Why did Ethereum Classic stay on proof of work?

Its site states a commitment to proof of work "indefinitely in pursuit of decentralization maximalism," arguing it is "the only one known to provide Sovereign Grade Censorship Resistance," and lists specific objections to proof of stake including complexity, staking custody centralization and nothing-at-stake.

What was the Thanos upgrade?

ECIP-1099, which doubled the mining epoch length from 30,000 to 60,000 blocks at block 11,700,000, halving DAG growth and, in the proposal's words, keeping 4 GB graphics cards "supported for an additional 3+ years." The resulting algorithm is called Etchash.

Where can you buy Ethereum Classic?

Availability depends on your country or US state. See where to buy Ethereum Classic for the exchanges serving your jurisdiction, and Exchanges to compare fees and kyc requirements.