Ethereum Activates ‘BPO’ Hard Fork; Blob Limit Hits 21 as Gas Fees Stabilize
Ethereum’s second Blob Parameter-Only fork raises the blob limit to 21, expanding data capacity to 2.6MB per block as ETH holds $3,226.
Ethereum successfully executed its second Blob Parameter-Only (BPO) hard fork early Wednesday, raising the network’s blob limit from 15 to 21. The upgrade, designed to decouple data availability scaling from complex code changes, immediately expanded block capacity to roughly 2.6 megabytes. ETH held steady at $3,226 (+1.4%) following the activation.
The Technical Delta
The fork modifies two critical parameters: the blob target increased from 10 to 14, and the hard cap rose to 21. With each blob carrying 128 kilobytes, the network can now process significantly more rollup data per block without congesting the execution layer.
Core developers shifted to BPO forks, lightweight upgrades that tweak specific variables, after the Fusaka update in late 2025. This strategy allows the network to react faster to rollup demand than the traditional, annual hard fork cycle permits.
“The BPO2 fork highlights that Ethereum’s scalability is now determined by parameters rather than fixed procedures. Blob space is far from being maxed out,” noted Andrew Gross, a technical communications specialist at Blockscout.
Institutional Context: Fee Stabilization
The upgrade addresses a specific pain point: volatility. Since the first BPO fork in December 2025, YCharts data indicates mainnet gas fees have decoupled from L2 activity spikes. By dedicating more space to blobs (temporary data storage for rollups), Ethereum prevents L2 settlement surges from bidding up gas prices for standard mainnet users.
Market makers anticipate this will force a repricing of risk for L2 operators, who can now guarantee faster settlement times with the expanded throughput.
Outlook: The Road to Glamsterdam
Attention now shifts to the “Glamsterdam” hard fork, slated for mid-2026. Preliminary specifications suggest Glamsterdam will introduce “perfect parallel processing” via Block Access Lists (EIP-7928) and potentially raise the gas limit to 200 million. Until then, the BPO framework remains the primary lever for incremental scaling.
