Ethereum's Fusaka Upgrade: Scaling Toward 12,000 TPS Future by 2026

Ethereum’s Fusaka upgrade, a critical step in the network’s scalability roadmap, is set to activate its first public testnet on October 1, 2025, with the Holesky testnet. This marks the beginning of a phased rollout across testnets, culminating in a mainnet launch on December 3, 2025. The upgrade introduces a 60 million gas limit default, a fivefold increase from the current 30 million, and incorporates Peer Data Availability Sampling (PeerDAS) to enhance data capacity and reduce costs for rollupsEthereum Fusaka Upgrade Targets Dec 3 Mainnet Launch^[1]. Developers confirmed the schedule during the ACDC 165 call, with Holesky followed by Sepolia on October 16 and Hoodi on October 30Ethereum Sets Fusaka Upgrade Timeline: Testnets in October, …^[2].

The gas limit hike is a cornerstone of Fusaka’s scalability goals. By raising the block gas limit to 150 million units, Ethereum aims to quadruple its throughput, enabling faster transaction processing and lower fees. Early testing on Devnet-5 showed blob capacity doubling within two weeks of activation, a key indicator of the upgrade’s potential to support Layer 2 solutionsEthereum Fusaka Upgrade Targets Dec 3 Mainnet Launch^[1]. PeerDAS further optimizes resource usage by allowing validators to sample peer data instead of downloading entire datasets, streamlining validation and improving network efficiencyCountdown to Fusaka: Ethereum Locks Dates for …^[3].

The testnet rollout strategy emphasizes sequential validation to mitigate risks. Holesky, despite its impending deprecation, was chosen as the first testnet to ensure robust peer sampling mechanicsEthereum Fusaka Upgrade Timeline On Testnets^[4]. Sepolia and Hoodi will follow, each serving as a checkpoint for bug detection and performance optimization before mainnet deployment. Mid-week activation times (e.g., October 2 for Holesky) were selected to align with developer call schedules and avoid conflictsEthereum Fusaka Upgrade Timeline On Testnets^[4].

Fusaka’s technical upgrades extend beyond gas limits and data availability. The upgrade includes Verkle Trees for leaner proofs, enhanced EVM performance, and increased smart contract code size (from 24KB to 48KB). These changes are expected to empower developers to build more complex decentralized applications while maintaining decentralizationEthereum Fusaka Upgrade Targets Dec 3 Mainnet Launch^[1]. Analysts estimate that by 2026, PeerDAS could enable Ethereum to process up to 12,000 transactions per second, rivaling centralized systems in throughputCountdown to Fusaka: Ethereum Locks Dates for …^[3].

The mainnet launch on December 3 will be followed by the Glamsterdam upgrade in 2026, which is anticipated to focus on further scalability enhancements such as the full EVM Object Format (EOF) and faster block timesEthereum Fusaka Upgrade Targets Dec 3 Mainnet Launch^[1]. Developers stress that the multi-stage approach ensures rigorous testing, with each testnet phase providing critical insights for mainnet stability. For users, the upgrade will be largely seamless, with wallets and exchanges automatically integrating changes. Validators and node operators, however, must upgrade their clients to avoid penaltiesCountdown to Fusaka: Ethereum Locks Dates for …^[3].

The Fusaka upgrade represents a pivotal advancement for Ethereum’s infrastructure, balancing innovation with operational resilience. By prioritizing behind-the-scenes improvements over user-facing features, the upgrade lays the groundwork for a more scalable and efficient blockchain ecosystem. As testnets activate over the next month, the community will closely monitor performance metrics to validate the upgrade’s potential to redefine Ethereum’s role in decentralized finance and enterprise applicationsEthereum Fusaka Upgrade Targets Dec 3 Mainnet Launch^[1].