ETH’s Fusaka Upgrade Delayed to December, Blob Capacity Set to Double
is pushing back its much-anticipated Fusaka hard fork to December 3, marking another chapter in its evolution. The upgrade includes 12 new ETH Improvement Proposals (EIPs) designed to improve the network’s scalability, reduce costs, and bolster security.
Blob Capacity Grows in Two Phases
One of the largegest changes in Fusaka is that blob capacity, which is how much large data (“blobs”) can be stored, will more than double. However, this increase won’t happen all at once.
The first blob capacity increase is scheduled for about December 17, followed by a second hard fork on January 7, 2026, that will further boost blob limits. At launch, Fusaka will set the max blob count under BPO1 (Blob-Parameter Only) at 15 and under BPO2 at 21. These adjustments pertain only to blob target and limit parameters, meaning these “BPO forks” don’t require all clients to upgrade.
Why Blobs Matter?
Blobs are useful because they allow large data sets to be stored off-chain. This assists work more efficiently and cuts the transaction cost burden on the main chain.
Since the prior Dencun upgrade, blob usage has already been on the rise. For example, the average blob count per block is now about 5.1, versus just 0.9 back in March 2023. This trend highlights how critical blob scaling has become for .
Testing and Security Measures Ahead of Time
Before the December rollout, ETH will run public testnets between ahead October and mid-November so that developers and users can catch bugs and test new behavior. Plus, there’s a four-week code audit in progress with a $2 million bounty for anyone who finds and reports issues in the Fusaka codebase. These steps show how carefully the is handling the upgrade, aiming to balance innovation with securety.
Where This Fits in ETH’s Upgrade Path
Fusaka follows the Pectra upgrade, which introduced features like layer-2 enhancements, account abstraction, and increased Block confirmer staking limits. The focus with Fusaka is accelerating scaling and making ETH more efficient, particularly for those layer-2 rollups and heavy off-chain data usage. With higher blob capacity and stronger testing measures, ETH is preparing itself for the next stage of adoption and long-term network growth.
