Why Classic?
Start here to get the lowdown on Etherum Classic's reason for being and unique value proposition
Further reading on the foundations that underpin ETC
Practical tutorials and walkthroughs for interacting with the network in a number of ways
A collection of videos and podcasts to keep you informed on ETC concepts and happenings

Protocol Upgrades

Ethereum Classic, despite its histroy, is not against all types of Hard Fork. Far from it; Hard Forking allows the protocol to be upgraded, to fix bugs, and add features that further the goal of enabling developers to "Build Unstoppable Applications".

The types of Hard Fork that Ethereum Classic will never implement are those like The DAO Fork, which do not address a defect in or enhancement of the protocol itself, but instead override Code is Law by modifying Smart Contracts in the application layer.

Ethereum Classic strategically maintains maximal compatibility with upstream Ethereum's EVM, which means contracts deployed to ETH can also be deployed to ETC, and Ethereum Classic inherits many valuable innovations born through research on Ethereum.

ETC Fork History


Block 0

Launched under the slogan "Build Unstoppable Applications", Frontier was a live, but barebones implementation of the Ethereum project. It followed the successful Olympic testing phase. It was intended for technical users, specifically developers. Blocks had a gas limit of 5,000. This ‘thawing’ period enabled miners to start their operations and for early adopters to install their clients without having to ‘rush’.

Ice Age

Block 200,000

The frontier thawing fork lifted the 5,000 gas limit per block and set the default gas price to 51 gwei. This allowed for transactions – transactions require 21,000 gas.


Block 1,150,000

The Homestead fork looked to the future. It included several protocol changes and a networking change that gave Ethereum the ability to do further network upgrades.

Gas Reprice

Block 2,500,000

ECIP-1015 was Ethereum Classic's First independent protocol upgrade after the DAO Hard Fork, which involed long-term gas cost changes for IO-heavy operations to mitigate transaction spam attacks.

Die Hard

Block 3,000,000

The Die Hard fork delayed the difficulty bomb, repriced the EXP opcode and implemented replay protection, setting ETC's Chain ID to 61.


Block 5,000,000

ECIP 1017 makes Ethereum Classic more Bitcoin-like by introducing an upper bound on the maximum absolute number of ETC and a method of degraded emission over time.

Defuse Difficulty Bomb

Block 5,900,000

The Difficulty Bomb is delayed, with no other changes.


Block 8,772,000

Enabled the outstanding Ethereum Foundation Spurious Dragon and Byzantium network protocol upgrades on the Ethereum Classic network in a hard-fork code-named Atlantis to enable maximum compatibility across these networks.


Block 9,573,000

Enabled the outstanding Ethereum Foundation Constantinople and Petersburg network protocol upgrades on the Ethereum Classic network in a hard-fork code-named Agharta to allow maximum compatibility across these networks.


Block 10,500,839

Enabled the outstanding Ethereum Foundation Istanbul network protocol upgrades on the Ethereum Classic network in a hard-fork code-named Phoenix to enable maximum compatibility across these networks.


Block 11,700,000

ECIP 1099 calibrated the epoch length used in DAG calculations, switching from ETHash to ETCHash, It increased the network's security by allowing GPUs with 4GB of memory to mine ETC.


Block 13,189,133

Enabled the Ethereum Foundation Berlin network protocol upgrade features, reaching maximum compatibility with Ethereum.


Block 14,502,000

Enabled the Ethereum Foundation London network protocol upgrade features, maintaining maximum compatibility with Ethereum.

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