Ethereum's Sepolia test network activated the Glamsterdam upgrade on October 6 at epoch 353,024, producing blocks with a gas limit of nearly 200 million — more than three times the 60 million cap on Ethereum mainnet. Gas is the unit measuring computing work on Ethereum, and the block gas limit caps how much of that work fits into a single block.

The 200 million figure was scheduled in a commit tied to epoch 353,024, a 6.4-minute time marker in Ethereum's calendar that began at 13:53:36 UTC. Sepolia is a practice network whose tokens carry no real value, allowing developers to test protocol changes without financial risk. It previously staged the Merge rehearsal on July 6, 2022, when it switched to proof of stake ahead of mainnet.

How much capacity did Sepolia actually use?

Blocks on the testnet consumed only a fraction of the new headroom. A snapshot of 25 consecutive blocks on Etherscan, taken on October 8 — blocks 11,872,013 through 11,872,037 — shows gas use ranging between 47.1 million and 85.9 million, roughly 24% to 43% of the limit.

A higher ceiling does not translate into three times as many transactions. It means a block can hold more work when demand materializes. For everyday users, that headroom helps keep fees from spiking during congestion, because fee spikes occur when users outbid each other for space in the next block.

What are the operational consequences?

Bigger blocks place heavier demands on validators, the operators that stake ETH as collateral to check and confirm each block. Ethereum Foundation researchers had warned that limits above 40 million could "fail to propagate as expected" across the network, which is why the limit has historically moved up in small increments.

One such increment was a 52%-to-48% validator vote in February 2025 that raised the limit from 30 million to 32 million. The limit later doubled to 60 million during 2025, and the Fusaka upgrade, which went live on December 3, 2025, made 60 million the protocol default.

Two changes on Ethereum's roadmap are designed to help the network carry more load safely:

• Block-level access lists record which accounts and data each block touches, letting machines verify many transactions at once rather than one by one.
• Enshrined proposer-builder separation moves the auction that decides who assembles each block — today run through outside middleware — into Ethereum's own protocol rules.

Ethereum co-founder Vitalik Buterin sketched the longer arc in July, describing a plan to replace almost every major piece of the protocol over three to four years. Glamsterdam is the nearer-term step, and developers describe a possible gas-limit increase toward roughly 200 million after it.

What happens next?

The announcement sets no date for the Hoodi testnet, another public test network, and schedules no mainnet upgrade. Ethereum's main network keeps its 60 million gas limit for now, and any move toward mainnet capacity expansion will depend on how Glamsterdam performs under Sepolia's test conditions.