Ethereum Fusaka Upgrade Slated for Dec 3 With Scaling Boosts

Ethereum’s core developers have set December 3, 2025 as the tentative mainnet date for the Fusaka upgrade.

Researcher Christine D. Kim detailed the decisions from developer call , where teams locked the rollout sequence after weeks of testing. The dates remain provisional until final epoch numbers are confirmed in the coming days.

The schedule starts with a code freeze on September 22 and client releases around September 25. Fusaka then activates on Holesky on October 2 at 12:06:24 UTC (epoch 165,376), followed by Sepolia on October 16 at 14:12:48 UTC (epoch 273,152), and Hoodi on October 30 at 22:11:36 UTC (epoch 50,944). If all phases hold, the mainnet launch will follow on December 3, 2025.

Developers said testing on Devnet-5 shows blob capacity should more than double within two weeks after activation, a key data point for scaling analysis.

Fusaka is Ethereum’s next major hard fork, built to expand throughput while keeping the network decentralized. The upgrade introduces Peer Data Availability Sampling (), which lets validators confirm large blobs by sampling peers instead of downloading entire datasets.

Developers also aim to raise the block gas limit from 30 million to 150 million units, add Verkle Trees for leaner proofs, and sharpen EVM performance so smart contracts execute faster. Together, these features mark a significant capacity increase at the base layer.

Meanwhile, Glamsterdam is Ethereum’s next upgrade after Fusaka, according to the network’s schedule.

The blockchain’s core developers expect that to happen in 2026 and would likely focus on other scalability enhancements, such as the full EVM Object Format (EOF) and faster block times.