TLDR
Ethereum (ETH) Fusaka activated on 3 Dec 2025 at 21:49:11 (UTC), per the official client release announcement.
- Follow?on parameter upgrades: BPO1 on 9 Dec and BPO2 on 7 Jan, noted in an official thread.
- Key features include PeerDAS and a 60M L1 gas limit, improving L2 capacity and fees, per a network update.
Deep Dive
1. Activation Time
Fusakas exact mainnet activation was 3 Dec 2025 at 21:49:11 (UTC). The timestamp is confirmed in the geth client release (link above) and mirrored by a community notice from bitcoin/">BOB with the same time window in their post.
- The client release specifies node versions and timing to avoid sync interruptions, reinforcing this as the definitive activation reference (see the release above).
2. Follow?On Milestones
Two blob?parameter?only (BPO) steps follow Fusaka: BPO1 on 9 Dec 2025 and BPO2 on 7 Jan 2026, which increment blob capacity and stabilize blob fees. The dates and rationale appear in the Ethereum accounts thread and are also summarized in external coverage such as CCNs explainer.
- These steps are part of a phased scaling plan so capacity rises without destabilizing the fee market.
3. Why It Matters
Fusaka introduces PeerDAS (sampling blob data without full downloads) and raises the L1 gas limit to 60M, together enabling more L2 throughput and making fees more predictable across rollups. These design choices are laid out in a network update and in an analyst summary highlighting the gas limit change and blob fee reserve floor in coverage.
- PeerDAS reduces per?node bandwidth requirements while increasing aggregate blob capacity for L2s.
- A 60M gas limit increases L1 throughput, supporting higher data posting by rollups.
If you use L2s, you should gradually see cheaper, steadier fees and faster confirmations as sequencers adopt the new capacity. Builders can plan for higher throughput without raising node hardware requirements.
Conclusion
Fusaka went live on 3 Dec 2025 at 21:49 (UTC), with immediate capacity and efficiency benefits and two quick follow?ups (9 Dec and 7 Jan) to raise blob throughput further. The upgrades phased approach ties scaling to fee stability, setting up L2sand usersfor lower costs and better performance over the coming weeks.
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