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Understanding EIP-4844 and Blob Transactions

How Ethereum's blob transaction upgrade made posting Layer 2 data significantly cheaper.

6 min readPublished 2026-09-28

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The problem it addressed
What EIP-4844 introduced
Why blobs are cheaper
What to remember

Key takeaways

What to remember

EIP-4844 introduced blob transactions, a cheaper way to post rollup data to Ethereum.
Blobs use a separate fee market and are deleted after a limited retention period.
This upgrade was a step toward Ethereum's longer-term Danksharding roadmap.
It produced a real, measurable reduction in typical Layer 2 transaction costs.

The problem it addressed

Before this upgrade, Layer 2 rollups posted their transaction data to Ethereum as regular, relatively expensive calldata, which was a significant portion of a typical rollup transaction's overall cost.

What EIP-4844 introduced

EIP-4844 introduced "blob" transactions — a new, separate, and substantially cheaper way to post large data packets to Ethereum, specifically designed for rollups' data-availability needs rather than for smart contract execution.

Why blobs are cheaper

Blob data uses a separate fee market from regular transaction gas, reducing competition with ordinary Ethereum activity.
Blob data is automatically deleted from nodes after a limited retention window, since it's needed only for a temporary verification period, not permanent storage.

Why it matters

This directly reduced typical Layer 2 transaction costs

Since data-posting was a major cost component for rollups, this upgrade produced a real, measurable reduction in typical Layer 2 transaction fees shortly after activation.

What to remember

EIP-4844 introduced blob transactions, a cheaper way to post rollup data to Ethereum.
Blobs use a separate fee market and are deleted after a limited retention period.
This upgrade was a step toward Ethereum's longer-term Danksharding roadmap.
It produced a real, measurable reduction in typical Layer 2 transaction costs.