Author | Tanay Ved, Coin Metrics
Compiled by | GaryMa WuShuo Blockchain
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Key Takeaways
Fusaka scales Ethereum’s scalability by increasing blob capacity and implementing a more efficient data availability system (PeerDAS).
A higher 60 million gas limit and execution layer optimizations significantly boost L1 throughput.
Improved fee mechanisms and UX upgrades lay the foundation for a more unified and cost-effective L1–L2 ecosystem.
Fusaka Overview
Ethereum will undergo the “Fusaka” hard fork at 21:49 UTC on December 3, 2025 (slot 13,164,544). Fusaka combines the Osaka execution layer upgrade with the Fulu consensus layer upgrade, continuing the naming tradition of past forks.
Following May’s Pectra, Fusaka is a significant step in Ethereum’s scaling roadmap: enhancing L1 performance, expanding blob capacity, improving rollup cost-efficiency, and bringing UX improvements. It also introduces the Blob Parameter Only (BPO) fork mechanism, enabling safe increases in blob capacity as rollup demand grows. Earlier this year, the Ethereum Foundation announced the “Protocol” strategy, focused on three long-term goals: scaling L1, scaling blobs, and improving user experience. Fusaka is the first upgrade fully aligned with this unified vision, marking a turning point for Ethereum’s future scalability and accessibility.
This article outlines Fusaka’s key changes and analyzes their impact on Ethereum mainnet, Layer-2 rollups, transaction costs, and user experience.
Scaling Blobs
Last year’s Dencun upgrade introduced “blobs,” allowing rollups to store transaction data on Ethereum mainnet at lower costs. Since launch, blobs have seen significant adoption thanks to rollups like Base, Arbitrum, and Lighter. This has led to blob usage often nearing saturation (currently close to the target of 6 blobs per block), which could trigger exponential increases in rollup fees. As data availability demand continues to grow, blob space has become a key bottleneck in Ethereum’s scaling path, and Fusaka directly addresses this obstacle.
PeerDAS: Peer Data Availability Sampling
PeerDAS (EIP-7594), or Peer Data Availability Sampling, is arguably one of Fusaka’s most important upgrades and directly aligns with the core goals of scaling L1 and scaling blobs. PeerDAS introduces a more efficient way for Ethereum nodes to verify blob data availability. Instead of downloading full blob contents, nodes sample data fragments to check availability, maintaining the same level of security without increasing the burden on L1 consensus nodes.
Expected Impact:
Nodes only need to store about 1/8 of each blob, significantly increasing blob throughput without raising hardware requirements.
Enables Ethereum to safely boost blob throughput, which is the core driver of rollup capacity.
Lower data availability costs lead to cheaper L2 transactions and more reliable batch submissions.
Lays the foundation for full danksharding, increasing transaction throughput across the entire ecosystem. For example, Base mentioned in its blog that L2 scaling improvements after Fusaka will “double the chain’s throughput within 2 months.”
Blob Parameter Only (BPO) Fork
With PeerDAS reducing the bandwidth and storage burden for nodes validating blob data, Ethereum can now safely increase blob capacity. Fusaka introduces the Blob Parameter Only (BPO) fork mechanism, allowing the per-block blob limit to be raised over time. This mechanism lets Ethereum adjust blob parameters without a full hard fork, providing the protocol with more flexible and responsive scaling tools.
Upcoming BPO Fork
Expected Impact:
Higher DA bandwidth: Increases rollup capacity from 6 blobs to up to 128 blobs per block, significantly lowering L2 transaction fees.
Flexible scaling: Blob parameters can be dynamically adjusted as demand grows.
Gradual scaling path: Aligns with Ethereum’s roadmap for cheaper rollup execution and scalable data availability.
Blob Base Fee Adjustment
As blob capacity expands, Ethereum’s blob fee market will play a more important role in coordinating rollup demand. Currently, rollups pay almost nothing for blobs. Because demand is price inelastic, blob fees usually stay at the minimum of 1 wei, and prices do not always adjust smoothly with usage. This results in a “price-inelastic” fee mechanism, limiting its ability to respond to usage changes.
Fusaka addresses this by tying the lower bound of the blob base fee to a fixed ratio of the L1 base fee, preventing blob prices from dropping to zero and ensuring the fee adjustment mechanism remains functional as blob space scales.
Main Impact:
More stable blob pricing: Prevents the fee market from being stuck at the minimum price.
More predictable rollup economics: Ensures rollups pay a reasonable baseline for data availability, avoiding sudden or unstable fee spikes.
Minimal impact on user costs: Even with a lower bound, L2 data costs remain just a small fraction of a few cents, with virtually no impact on UX.
Long-term economic sustainability: Compensates nodes for handling higher blob throughput; blob fees currently contribute little to ETH burn, but as capacity expands, they may contribute more.
Scaling L1
Fusaka also places strong emphasis on L1 scaling. Through EIP-7935, it raises Ethereum’s default gas limit to 60 million, boosting Layer-1 execution capacity. This directly increases the number of transactions per block, enabling higher throughput, less congestion, and lower gas fees.
Expected Impact:
Higher throughput: More computation per block, increasing overall L1 capacity.
Supports more complex applications: Higher gas limits allow complex contracts to execute smoothly.
Less congestion during high load: Extra space reduces congestion during demand spikes.
Maintains low fees: Extra capacity supports the current low-fee environment (< 0.4 gwei).
In addition to the higher gas limit, Fusaka introduces a series of optimizations to make L1 execution more efficient and prepare for future scaling.
New per-transaction gas usage limit: Prevents a single transaction from occupying an entire block and lays the groundwork for future parallel execution.
ModExp precompile optimization: Recalibrates gas costs and sets clearer boundaries for related operations, ensuring resource usage remains predictable as throughput grows.
Network layer streamlining: Removes deprecated pre-merge fields, allowing Ethereum nodes to sync faster and more lightweight.
Improving User Experience (UX)
Fusaka introduces a series of updates to improve user and developer experience. Notably, EIP-7951 adds native support for the secp256r1 elliptic curve, a signature standard widely used by Apple Secure Enclave, Android Keystore, and most consumer hardware.
This means wallets and applications can directly integrate familiar authentication flows on Ethereum, such as Face ID, Touch ID, and WebAuthn.
This reduces onboarding friction for users and provides stronger security for both retail and institutional users.
These upgrades further modernize Ethereum’s developer experience and user interface, making it easier to build secure, mainstream-ready applications.
Conclusion
With Fusaka activated, the most immediate effects will be: lower rollup costs, higher blob throughput, and significantly improved L1 execution capacity.
Over time, greater blob space, lower costs, and steadily increasing L1 performance will reshape L2 settlement economics, impact ETH burning dynamics, and make the entire Ethereum ecosystem more unified and coordinated.
While the long-term value impact will still depend on demand and adoption speed, Fusaka lays a clearer and more scalable foundation for Ethereum’s next stage of growth: an ecosystem where L1 and L2 work together more efficiently, supporting more users, assets, and on-chain activity.
