Key Takeaways:
- Ethereum’s Fusaka hard fork is scheduled for December 3, with blob capacity increases rolling out in phases through January 2026.
- The upgrade introduces 12 EIPs focused on scalability, security, and cost reduction, with testnet deployments running from October to mid-November.
- Blob capacity will more than double, aiding layer-2 performance and lowering fees, with a $2M code audit launched to ensure upgrade security.
Ethereum developers have confirmed that the network’s next major upgrade, the Fusaka hard fork, will take place on December 3, 2025.
The upgrade will roll out 12 Ethereum Improvement Proposals (EIPs) focused on boosting scalability, enhancing security, and lowering costs.
Important decisions were made on today's Ethereum developer call, ACDC #165. Developers confirmed the public testnet schedule and BPO hard fork schedule for Fusaka.
— Christine D. Kim (@christine_dkim) September 18, 2025
Let's get into it. pic.twitter.com/mNrYMYyDj2
A central feature of Fusaka is the expansion of blob capacity, which supports storing large offchain datasets.
While Fusaka launches on December 3, the increase in blob capacity will be activated on December 17, followed by another related hard fork on January 7, 2026.
According to Ethereum researcher Christine D. Kim, these adjustments will more than double current blob capacity.
Developers also plan three public testnet deployments between October and mid-November.
The Fusaka roadmap includes five “Blob-Parameter Only” (BPO) forks, which modify blob-related targets without requiring client-side changes.
Blobs are crucial for layer-2 scaling and cheaper transactions, with average usage per block rising from 0.9 in March 2023 to 5.1 recently.
To ensure security, the Ethereum Foundation launched a $2 million bug bounty audit.
Fusaka follows the May 7 Pectra upgrade, which improved staking, account abstraction, and layer-2 efficiency.
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