Ethereum's Sepolia Testnet Fires Up Blocks Three Times Mainnet's Size
Ethereum's main test network just ran a live experiment in much bigger blocks. Sepolia switched on the Glamsterdam upgrade on October 6 and started producing blocks with a gas limit near 200 million — roughly three times mainnet's 60 million cap.
Gas limit is the ceiling on how much computation fits into a single block. Sepolia blew past the old number without coming close to filling it: a snapshot of 25 straight blocks on October 8 used between 47.1 million and 85.9 million gas, about a quarter to just under half of the new ceiling.
Room to spare, for now
That headroom is the whole point. Ethereum Foundation researchers had warned that limits above 40 million could fail to propagate across the network as expected, so the number has climbed in small steps rather than one big jump.
What Glamsterdam actually changes
Glamsterdam bundles two upgrades — Amsterdam on the execution layer and Gloas on consensus. It brings enshrined proposer-builder separation, which pulls the block-building auction into Ethereum's own rules, and block-level access lists that let machines verify many transactions at once instead of one by one.
There is more in the box: ETH transfer logs, a slot-number opcode, a larger maximum contract size, a deterministic factory contract, and new stack-manipulation instructions. Glamsterdam also rewrites gas accounting so it better reflects the resources a transaction actually uses.
Mainnet stays put
Nothing here changes Ethereum mainnet yet. No date is set for Hoodi, the other public testnet, and no mainnet upgrade is on the calendar, so the 60 million limit holds.
For anyone trading, bridging or farming on Ethereum, this is a preview rather than a switch. When the heavier blocks eventually land, fees and throughput are the numbers to watch — and history says the change will be slow. The limit only moved from 30 million to 32 million after a razor-thin 52%-to-48% validator vote in February 2025, and it took the Fusaka upgrade in December 2025 to make 60 million the default.