Ethereum’s Second BPO Hard Fork Unleashes 21-Blob Limit - Scaling Breakthrough Hits Mainnet

Ethereum just cranked up the data firehose. The network's second BPO hard fork is live, and with it comes a hefty bump in blob capacity—pushing the limit to 21 per block.

More Blobs, Fewer Bottlenecks

This isn't a minor tweak; it's a direct response to the crushing demand for block space from L2 rollups. Each blob is a dedicated data lane for these scaling solutions. By expanding from the previous cap, the upgrade effectively widens the highway, aiming to slash transaction fees and congestion that have been a persistent headache for users and developers alike.

The Mechanics of the Move

The hard fork executes a predefined parameter change within the consensus layer. No new opcodes, no fancy new virtual machinery—just a straightforward, albeit significant, increase in a key resource limit. It's a surgical strike on scalability, leveraging the blob-carrying architecture introduced in earlier upgrades.

Implications for the Rollup Ecosystem

For protocols like Arbitrum, Optimism, and zkSync, this is rocket fuel. More blob space means cheaper data availability, which translates directly to lower costs for end-users. It strengthens Ethereum's core thesis as a settlement layer, outsourcing execution while securing data. The race for the cheapest and fastest rollup just entered a new lap.

A Nod to the Roadmap

This increment to 21 blobs is a milestone, not the finish line. It reflects a continued, stepwise approach to scaling—prove the network's stability with increased load, then push further. Watch for the next target number to emerge from core developer calls as pressure mounts.

The upgrade lands as ETH price action remains, predictably, disconnected from technical prowess—because in crypto, fundamentals are just a suggestion when the futures market gets a sniff of leverage. The network builds; the traders gamble. Some things never change.

Blobs help keep fees low and the main network stable

Apart from enhancing speed, blobs also help maintain the Ethereum gas fee at a more moderate level. Gas fees are the tiny charges that users pay to send transactions or run smart contracts on the Ethereum network.

When many people use the network simultaneously, fees tend to increase. Layer 2 networks can utilize blobs to transfer data at a rapid pace, thereby reducing the need for a larger number of transactions to compete for space on the main Ethereum network.

It helps to reduce the traffic jams and stabilizes fees. This is a huge advantage for Ethereum developers. As layer 2s mainly use blobs, they help to regulate the main Ethereum network more evenly.

Ethereum plans bigger upgrades in 2026

This second BPO hard fork is only one component in a much larger strategy. Developers also discussed increasing the gas limit in Ethereum, for example, at an Ethereum All Core Developers meeting on December 15. It represents the limit on transaction and smart contract actions in a given block. At this point, the gas limit is 60 million. 

Developers had discussed raising it to 80 million after the second BPO hard fork. In this case, Ethereum blocks WOULD include more activity, which could further improve speed and lower fees. Even further down the path, Ethereum is designing the Glamarsterdam hard fork, which it expects to launch later in 2026. 

This upgrade will place a strong emphasis on scalability. It will allow the gas limit to increase gradually to as much as 200 million. It’ll also enable something called perfect parallel processing. Now, Ethereum handles transactions primarily one after another, in the same way that cars FLOW in a single lane. 

Perfect parallel processing will enable Ethereum to process numerous transactions simultaneously, much like cars traveling on a multi-lane highway. 

This will be accomplished with the benefit of Block Access Lists, part of Ethereum Improvement Proposal 7928 (EIP-7928). This improvement will help Ethereum accommodate significantly more demand without slowing down.

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