Ethereum has officially activated its Fusaka upgrade on mainnet as of December 3, 2025, a major hard fork that reshapes the network’s scaling future. As part of the broader Surge phase of Ethereum’s long-term roadmap, Fusaka dramatically boosts the chain’s data capacity, reduces Layer 2 (L2) fees, and improves the overall user experience.
The upgrade’s name blends “Fulu” (consensus layer) and “Osaka” (execution layer), reflecting its deep changes across both sides of Ethereum’s architecture.
A New Era of Data Availability
At the core of Fusaka is Peer Data Availability Sampling (PeerDAS), the most significant change introduced in this upgrade. Before Fusaka, every node had to download all blob data produced by L2s, which created heavy bandwidth and hardware requirements. With PeerDAS, validators now verify data availability by sampling small, randomized portions of blobs.
This drastically reduces validator load, strengthens decentralization, and opens the door for an enormous boost in L2 throughput. It also makes running nodes more accessible, which supports the long-term health and resilience of the Ethereum network.
Lower Fees Across the L2 Ecosystem
Because Fusaka expands blob capacity and handles data more efficiently, L2s like Arbitrum, Optimism, zkSync, and Base are expected to see 40–60% lower transaction fees. With the network now capable of supporting 100,000+ L2 transactions per second, the upgrade positions Ethereum as an even more scalable settlement layer for the entire rollup ecosystem.
This fee reduction is one of the most immediate and noticeable impacts users will experience.
Higher Block Gas Limit on Layer 1
Fusaka raises the mainnet’s default block gas limit from ~36 million to 60 million, allowing Layer 1 to process more transactions and execute more complex smart contracts per block. While Ethereum’s long-term strategy relies on L2 scaling, this increase gives the base layer more breathing room and improves throughput for high-demand periods.
Better UX and Modern Cryptography Support
A major quality-of-life enhancement comes from the introduction of secp256r1 (P-256) signature support, a cryptographic standard widely used in modern smartphones and security devices.
This unlocks:
- •Device-native biometric authentication (e.g., Face ID, Touch ID)
- •Mnemonic-less wallets
- •Enhanced hardware-level security
With Fusaka, Ethereum takes a significant step toward eliminating seed phrases and making web3 authentication feel like any modern mobile app.
More Predictable Blob Fees
Through EIP-7918, the upgrade stabilizes blob fees by connecting them to execution layer costs and introducing a fee reserve mechanism. This predictability helps L2 teams plan infrastructure budgets more effectively and keeps the broader rollup economy on steady footing.
Built-In Support for Future Upgrades
Fusaka also introduces a Blob-Parameter-Only (BPO) fork mechanism, giving Ethereum the ability to safely expand blob capacity between major hard forks. Instead of waiting for a large network upgrade, developers can gradually increase blob limits when needed, accelerating scaling improvements throughout the Surge phase.
A Major Milestone for Ethereum’s Roadmap
The Fusaka upgrade strengthens Ethereum’s position as the leading decentralized settlement layer. With drastically reduced L2 costs, improved data availability, higher L1 capacity, and a more user-friendly cryptographic foundation, the network is now better equipped to handle the next wave of on-chain activity.
As Ethereum continues progressing through the Surge, future upgrades will build on Fusaka’s groundwork, pushing the ecosystem toward a world where global-scale applications run seamlessly on decentralized infrastructure.