Ethereum is moving into the final testnet phase of its Fusaka upgrade, the last significant step prior to its anticipated mainnet launch on Dec. 3. This update brings a per-transaction gas cap of approximately 16.78 million units to improve block efficiency and prepare the network for parallel execution.
Active on the Holesky and Sepolia testnets, this change is intended to prevent single transactions from utilizing the entire gas limit of a block. Previously, individual transactions could consume up to the complete block gas limit of around 45 million, posing potential denial-of-service threats and limiting scalability.
This gas cap restricts the processing power a single transaction can utilize, ensuring that no single transaction can monopolize a block, thereby allowing the network to handle activities more equitably.
By implementing a per-transaction gas limit cap, Ethereum aims for more efficient and predictable block composition, allowing multiple smaller transactions to fit within a block.
This update is part of Ethereum’s broader shift towards parallel execution, a significant milestone in its roadmap, which will enable simultaneous transaction processing.
The introduction of transaction gas caps followed the launch of the Fusaka upgrade on the Sepolia testnet about a week ago, which raised the complete block gas limit from roughly 45 million to 60 million.
The next stage of the Fusaka upgrade is set for rollout on the Hoodi testnet on Oct. 28, with mainnet deployment expected in December 2025.
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Grasping the Fusaka upgrade
The Fusaka upgrade (EIP-7825) is a key component of Ethereum’s roadmap, following the Dencun upgrade in March 2024 and the Pectra upgrade on May 6, 2025.
This upgrade implements several changes: it increases Ethereum’s default block gas limit to 60 million, establishes a per-transaction gas cap of 16.77 million under EIP-7825, and introduces PeerDAS — the upgrade’s primary feature.
PeerDAS, or Peer Data Availability Sampling, enables Ethereum nodes to store only small random segments of layer 2 “blob” data rather than the entire data set. This method maintains network security while decreasing hardware requirements and facilitating more affordable, higher-throughput scaling for layer-2 networks.
Glamsterdam, the subsequent upgrade post-Fusaka, will concentrate on Ethereum’s execution layer and introduce EIP-7928, marking the network’s first significant increment towards parallel transaction processing.
Gabriel Trintinalia, a protocol Engineer at Consensys’ client Besu, remarked to Contelegraph, “These testnet upgrades are vital in fostering confidence ahead of the mainnet fork, allowing client teams, validators, and the ecosystem to validate performance, spot edge cases, and fine-tune parameters before activation.”
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