Crypto Gloss

Ethereum Dencun Upgrade

Ethereum activated the Dencun upgrade on March 13, 2024, combining changes to its Cancun execution layer and Deneb consensus layer. The best-known change was EIP-4844, also called Proto-Danksharding. It added blob-carrying transactions so Layer 2 rollups could publish data to Ethereum in a separate, temporary data-availability market.

What EIP-4844 changed

A blob carries data needed by a rollup but is not readable by Ethereum smart contracts as ordinary execution data. The transaction commits to the blob using KZG cryptography; nodes propagate the blob data separately and retain it for a limited period. Ethereum’s documentation describes a retention window of about 18 days, after which ordinary nodes may prune the blob. Rollups and other services can keep archival copies when they need historical access.

Before EIP-4844, rollups commonly posted compressed transaction data as calldata, which competed for ordinary execution gas and was retained as part of Ethereum’s permanent chain data. Blob transactions created a separate fee market for this temporary data. That gives rollups another way to pay for data availability without putting the full blob contents into the EVM state.

What users may notice

Dencun was designed to lower the cost of publishing rollup data, but it does not set one fixed transaction price for every L2. A user’s final fee still depends on the rollup’s own pricing and batching, demand for blob space, other execution costs, and whether the rollup chooses blobs or calldata. Ethereum’s Dencun guide also cautions that the upgrade primarily targets L2 costs; it does not directly make ordinary Ethereum mainnet transactions dramatically cheaper. If blob space is busy, a rollup may use calldata instead.

The change also did not make every EVM-compatible chain cheaper. The benefit applies to rollups that publish data to Ethereum and use the blob mechanism. A separate chain that does not settle its data on Ethereum does not get this benefit merely because it supports the EVM.

Dencun was a starting point, not full danksharding

At launch, EIP-4844 used a target of three blobs per block and a maximum of six. Those were Dencun-era parameters, not a timeless capacity limit. EIP-7691 later raised the target and maximum to six and nine respectively under the Pectra upgrade. Later protocol changes can adjust capacity again, so launch numbers should not be presented as the current settings.

Proto-Danksharding did not distribute blob storage through full data-availability sampling. It introduced the transaction format and fee market that rollups could use while further scaling work continued. Ethereum’s roadmap treats broader data availability sampling and Danksharding as separate work; Dencun itself did not deliver a fixed date for those later steps.

Why the fee debate continues

Cheaper blob space can help rollups reduce data costs, but the same low price can mean less direct fee revenue for Ethereum while capacity is underused. Higher capacity may give rollups room to grow, although demand and the pricing rules determine whether that space becomes scarce. The technical change therefore creates a trade-off between lower L2 data costs, network capacity, and the amount users pay for blob space.

Social Media Sentiment

A bounded example is a May 2025 r/ethereum discussion about blob fees after a capacity increase. Participants disagreed about whether low blob prices were a temporary result of added capacity or a longer-term revenue trade-off, while some argued that more L2 activity could eventually use the extra space. It is one dated discussion, not a representative measure of current Ethereum users or blob-market conditions.

Last updated: 2026-10

Related Terms

See Also

Sources