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Ethereum Schedules Fusaka Hard Fork for December With Major Blob Capacity Upgrades

Ethereum Schedules Fusaka Hard Fork for December With Major Blob Capacity Upgrades

Ethereum’s Fusaka upgrade, now finalized on the Holesky testnet, introduces PeerDAS to reduce Layer-2 and validator costs, with two more testnet runs before its December 2025 mainnet launch.

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Fact Check
Multiple sources (Cointelegraph, Yahoo Finance, The Block) corroborate that the Fusaka hard fork is scheduled for December 3rd. While the main fork enables the changes, the evidence states that the blob capacity increase will be implemented via subsequent, smaller hard forks starting just two weeks later, also in December. Therefore, the statement is an accurate summary of the scheduled events.
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Summary

Ethereum’s Fusaka hard fork has been successfully deployed on the Holesky testnet, a critical step toward its scheduled Dec. 3, 2025, mainnet release. The upgrade will reduce operational costs for institutional users and Layer-2 networks, with PeerDAS optimizing data verification to lower expenses for validators and rollups. Developers plan two additional testnet deployments on October 14 and October 28 before confirming the mainnet rollout. Fusaka also includes staged increases in blob capacity to alleviate scaling pressures and follows the Pectra upgrade of May 2025.

Terms & Concepts
  • Blob: A large offchain data storage unit used to improve Ethereum’s scalability and lower Layer-2 transaction costs.
  • Validator Client: A software running Ethereum’s proof-of-stake system, responsible for proposing and verifying blocks.
  • PeerDAS: A data availability sampling mechanism in Ethereum designed to optimize verification and reduce costs for Layer-2s and validators.