Ethereum developers successfully executed the network’s second “Blob Parameter-Only” (BPO) hard fork at 1:01 UTC on Wednesday, pushing the maximum number of data blobs per block from 15 to 21. The upgrade, confirmed by Ethereum Foundation researcher Alex Stokes, immediately expands the mainnet’s data availability capacity to roughly 2.69 megabytes per block.
The Numbers
The “BPO2” fork adjusts two critical parameters in the consensus layer without requiring a full client upgrade cycle:
- Target Blobs: Increased to 14 (previously 10).
- Maximum Blobs: Increased to 21 (previously 15).
With each blob carrying 128 kilobytes of data, this adjustment allows Layer 2 rollups like Arbitrum, Optimism, and Base to post significantly more transaction batches to the mainnet in a single block. The move is designed to suppress fee volatility on L2s by increasing the supply of “blobspace” ahead of demand spikes.
“The Ethereum Blob Pressure Optimization (BPO2) upgrade has officially taken effect on the mainnet,” Stokes confirmed shortly after activation.
Institutional Context
This activation marks the second execution of Ethereum’s new agile scaling strategy. Unlike traditional hard forks which require months of coordination, BPO forks treat blob limits as configurable parameters. The first BPO fork occurred on December 9, 2025, just weeks prior.
Market response was muted but stable, with Ether (ETH) holding the $3,300 level following the upgrade. The rapid cadence of these parameter adjustments signals a shift in the Ethereum Foundation’s approach: aggressively scaling data throughput to maintain dominance against alternative data availability layers (DA) like Celestia.
Developers indicated this specifically targets the “cold-start problem” in blob fee markets, ensuring that as L2 usage ramps up in Q1 2026, the network does not hit a saturation wall that would spike gas prices.
