On August 5, 2021, the Ethereum network underwent one of the most significant upgrades in its history. The London Hard Fork activated at block #12,965,000 at approximately 12:33 PM UTC, introducing a suite of changes that would fundamentally reshape how users interact with the second-largest blockchain. With Bitcoin holding steady above $40,800 and Ethereum trading near $2,827 on the day of activation, the crypto market watched closely as years of planning finally came to fruition.
TL;DR
- The London Hard Fork activated on August 5, 2021, at block #12,965,000 on the Ethereum mainnet
- Five Ethereum Improvement Proposals were implemented, with EIP-1559 being the most consequential
- EIP-1559 replaced the auction-based fee model with a base fee + priority fee system
- The entire base fee is now burned, reducing ETH supply and creating deflationary pressure
- Block gas limits doubled from 12.5 million to 25 million, targeting 50% utilization
What Changed With the London Upgrade
The London Hard Fork bundled five Ethereum Improvement Proposals: EIP-1559, EIP-3554, EIP-3529, EIP-3198, and EIP-3541. Each addressed different aspects of the network, but the flagship change was undoubtedly EIP-1559 — a proposal first put forward by Ethereum co-founder Vitalik Buterin back in 2019.
For years, Ethereum users had struggled with unpredictable gas fees. The old system operated like a blind auction: users would guess how much to pay for their transaction to be included in a block, often overpaying to ensure processing. EIP-1559 replaced this cumbersome model with a more transparent two-part fee structure consisting of a base fee and an optional priority fee.
How the New Fee System Works
The base fee represents the minimum payment required for a transaction to be included in a block. Unlike the old auction model, this fee is algorithmically determined based on network congestion and is recalculated every block. The base fee can increase or decrease by up to 12.5% per block, providing smoother fee adjustments and greater predictability for users.
For users who need faster processing, the priority fee — essentially a tip to validators — remains available. This two-tiered approach means everyday transactions cost less during low-activity periods, while urgent transactions can still pay a premium for priority inclusion.
EIP-1559 also doubled the maximum gas limit per block from 12.5 million to 25 million gas units, with a target block utilization set at 50%. When utilization exceeds this target, the base fee automatically increases, incentivizing users to reduce transaction volume and restoring balance to the network.
The Burning Mechanism and Its Economic Impact
Perhaps the most controversial — and from an investor perspective, exciting — aspect of EIP-1559 is its burning mechanism. The entire base fee paid by users is permanently removed from circulation. Miners, who previously collected all transaction fees, now receive only the priority fee portion. This shift sparked significant debate within the mining community, with some miners expressing concern that the change could reduce their revenue by 20-30%.
However, for ETH holders, the burning mechanism introduced a powerful deflationary force. By continuously removing ETH from circulation, EIP-1559 has the potential to make Ethereum net-deflationary during periods of high network activity — a characteristic that has drawn comparisons to Bitcoin’s fixed supply cap. The upgrade was widely viewed as a critical stepping stone on Ethereum’s path to transitioning from Proof of Work to Proof of Stake, a move that would eventually culminate in “The Merge.”
Market Reaction and Testing
Prior to mainnet activation, the London Hard Fork had been tested extensively across the Ropsten, Goerli, and Rinkeby test networks, generating a full spectrum of reactions within the crypto community — from enthusiastic support to vocal opposition. Following activation on August 5, ETH price action showed resilience, with the token reversing early losses and trading higher in the hours after the fork went live.
Why This Matters
The London Hard Fork represented far more than a technical upgrade. It was a fundamental reimagining of Ethereum’s economic model. By introducing predictable fees, burning base fees to reduce supply, and setting the stage for Proof of Stake, EIP-1559 addressed some of Ethereum’s most persistent criticisms. For the broader crypto industry, August 5, 2021 marked the day Ethereum began its transformation from a high-fee, inflationary network into a more efficient, user-friendly, and potentially deflationary platform. The long-term impact on ETH tokenomics and the network’s competitiveness against emerging smart contract platforms would prove to be one of the defining narratives of the 2021 bull cycle.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. Past performance is not indicative of future results. Always conduct your own research before making investment decisions.
block 12965000 was such a moment. watching the base fee mechanism go live in real time after years of blind auction chaos felt like ethereum finally growing up. the doubling of gas limits from 12.5m to 25m was underappreciated too
Five EIPs bundled into one fork and the only one anyone remembers is 1559. EIP-3554 pushing back the difficulty bomb and EIP-3529 reducing gas refunds for smart contracts were both crucial for the merge roadmap. The fee burning was the sexy headline but the technical foundation work mattered more long term.
eth at $2827 on activation day and everyone was calling for $5k by end of year. the deflationary narrative from base fee burning was powerful but people forget vitalik proposed this back in 2019 and it took two years just to get consensus on implementation
The base fee plus priority fee model was such an elegant solution to the blind auction problem. Before London you basically had to overpay to guarantee inclusion. The algorithmic adjustment based on block utilization finally made gas fees somewhat predictable.
btc holding above $40800 while eth was going through its biggest upgrade was telling. the eth/btc ratio barely moved on london day because the market had already priced it in months ahead. buy the rumor sell the news even applies to hard forks