After Ethereum's Cancun upgrade in March 2024, transfer fees on many Layer 2 networks dropped significantly. The key change behind this was the introduction of blobs through EIP-4844: temporary data blocks designed specifically for Layer 2 networks to store data for a limited time.

Layer 2 networks pay blob fees in $ETH when writing blob data to mainnet. Current price: 2240.39 (24h -0.25%).

■ What does Layer 2 write to mainnet?

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

■ What is a blob?

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

Blob data is not available to the EVM. Contracts can only access 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, allowing it to 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 Dencun 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 been raised further since then.

■ What this means for everyday users

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

■ In conclusion

In short, blobs are inexpensive data space for layer 2 networks that is stored for only a couple of weeks. They help Ethereum lower costs for layer 2 networks without increasing the long-term storage burden on nodes. If a project promises high returns, be skeptical.

What do you think? Join the discussion in the comments.