Blobs on Ethereum
Blobs are dedicated data storage spaces specified in EIP-4844, activated as part of the Dencun upgrade.
EIP-4844 serves as an interim solution to enhance the usage of Ethereum rollups by reducing transaction fees for users, bridging the gap until the implementation of full data sharding, which is expected to take a considerable amount of time.
Details about blobs:
- Blobs are included in a new transaction type called blob transaction (Type 3) (example)
- Each blob can store up to 128kb of data (example)
- Each block can include a maximum of 6 blobs (example)
- Each blob transaction can include a maximum of 6 blobs (example)
- Data posted to blobs:
- Cannot be accessed by EVM execution
- Is stored on the Beacon chain to ensure its availability
- Is only required to be stored for ~18 days, allowing blobs to be priced cheaper than calldata, which is stored forever
- Need only be stored by any one entity, and its authenticity can be verified against the KZG commitment stored permanently on the EVM
- Blob gas fee mechanism:
- Blobs have a separate gas fee market from calldata, ensuring that blob gas prices remain unaffected by network congestions caused by non-blob transactions
- Blob gas price mechanism is similar to EIP-1559, where it adjusts up to ±12.5% relative to the target blob count (currently set at 3) from the previous block
- Blob gas price remains constant if the blob count from the previous block equals the target of 3
- View the latest blob gas price at the View Blobs page
- Calculating blob transaction fee:
- Blob transaction fee = calldata fee + blob fee
- Calldata fee = calldata gas price * calldata gas used
- Blob fee = blob gas price * blob gas used
Impact on Rollups
Rollups that are posting batched data to blobs see an immediate transaction fee reduction on Ethereum.
The cost savings on Ethereum were then passed on to their users. As a result, ETH transfers on most rollups now cost less than $0.01.
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