My approach is to understand how something works before getting into it.

After Ethereum’s Cancun upgrade in March 2024, transaction fees on many Layer 2 networks fell significantly. The key change was the introduction of blobs through EIP-4844: a type of “temporary data block” designed specifically for Layer 2 networks to store data, which is kept only for a limited time.

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【What does Layer 2 need to write to mainnet?】

Layer 2 networks process a large number of transactions off the mainnet, but they need to send transaction data back to the Ethereum mainnet so that anyone can access the data and verify the results. Before the Cancun upgrade, this data could only be written into the calldata of regular transactions, competing for the same block space as other transactions and paying according to the same Gas rules. This cost made up the bulk of Layer 2 fees.

【What is a blob?】

EIP-4844 introduced a new type of transaction that carries blobs. Each blob consists of 4,096 data units of 32 bytes each, or about 128 KB. Blob data is stored by consensus-layer nodes for about 4,096 epochs, or roughly 18 days, after which it is deleted.

Blob data is not accessible to the EVM. Contracts can only see a versioned hash derived from the blob’s KZG commitment. Because the data is stored for only a couple of weeks and is not used in computation, it places a much smaller burden on nodes, so it can be offered to layer 2 networks at a lower price.

【A separate fee market】

Blobs have their own fee mechanism: each block has a target blob usage. When usage is above the target, the blob base fee goes up; when it is below the target, the fee goes down. The idea is similar to EIP-1559, and these fees are also burned.

When the Cancun upgrade went live, the target was 3 blobs per block, with a maximum of 6. The Pectra upgrade in May 2025 raised this to a target of 6 and a maximum of 9; the Fusaka upgrade in December introduced PeerDAS, and the limit has since been increased further.

【What does this mean for everyday users?】

For users transferring funds or trading on layer 2, the most immediate change is lower fees. However, layer 2 fees consist of two parts: the layer 2’s own execution fee and the cost of submitting data to mainnet. When demand for blobs surges, blob fees also rise, so layer 2 is not always equally cheap.

【Summary】

In a nutshell: blobs are low-cost data space for layer 2 networks that is kept for only a couple of weeks. They help Ethereum reduce costs for layer 2 without increasing the long-term storage burden on nodes. Every benefit comes with a corresponding risk, so understand the worst-case scenario first.

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Just my personal opinion—don’t take it too seriously.