After Ethereum's Cancun upgrade in March 2024, transfer fees on many Layer 2 networks dropped significantly. The key reason was blobs, introduced by EIP-4844: a kind of “temporary data block” designed specifically for Layer 2 networks to store data for a limited time.

Layer 2 networks pay blob fees when submitting blob data to mainnet, and these fees are also settled in $ETH . Current price: 2258.86 (24h +0.42%).

— What does Layer 2 write to mainnet? —

Layer 2 networks process a large number of transactions off mainnet, but they must send the transaction data back to 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 with other transactions for the same block space and paying gas fees under the same 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 chunks of 32 bytes each, about 128 KB in total. Consensus-layer nodes store blob data for about 4,096 epochs, or roughly 18 days, after which it is deleted.

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

— 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 mechanism 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 that 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 also rise, so layer 2 is not always equally cheap.

— A few final words —

In short: blobs are low-cost data space for layer 2 networks that is stored for only a couple of weeks. They reduce costs for layer 2 without increasing the long-term storage burden on nodes. Understanding this won’t make me money overnight, but it might help me avoid a few rookie mistakes. Cross-check information across multiple sources before deciding; don’t rely on just one person’s take.

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