Blob gas is a separate type of gas used to price the temporary data blobs introduced by Ethereum’s EIP-4844 upgrade. Unlike regular Ethereum gas, which primarily measures the computational work and permanent transaction data processed by the Ethereum network, blob gas is used specifically to price the storage and availability of temporary blob data.
Blob gas was introduced with Ethereum’s Dencun upgrade in March 2024 through EIP-4844, also called Proto-Danksharding.
The main purpose of blob gas is to make it cheaper for Ethereum Layer 2 networks to publish large amounts of transaction data to Ethereum.
How Does Blob Gas Work?
Ethereum now has a separate fee market for blob data.
When a transaction includes one or more blobs, the transaction pays a blob fee based on the current blob gas price and the amount of blob gas required.
A simplified way to think about it is:
Blob fee = blob gas used × blob gas price
The blob gas price changes depending on demand for blob space.
When many Layer 2 networks want to publish blobs at the same time, demand increases and blob gas can become more expensive.
When blob space is not heavily used, the blob gas price can fall.
What Is a Blob in Ethereum?
A blob is a temporary piece of data attached to certain Ethereum transactions.
The word “blob” stands for Binary Large Object.
Blobs were designed primarily for Ethereum Layer 2 rollups. Rollups can put transaction data into blobs instead of relying entirely on Ethereum’s more expensive calldata system.
The key characteristics of blobs are:
- They can contain large amounts of data.
- They are cheaper than traditional calldata for rollups.
- They are temporary rather than permanent.
- They have their own fee market.
- Smart contracts cannot directly read their contents.
Blob Gas vs Regular Gas
Blob gas and regular Ethereum gas are related but serve different purposes.
| Feature | Regular Gas | Blob Gas |
|---|---|---|
| Used for | Computation and transaction execution | Blob data availability |
| Main users | Ethereum transactions and smart contracts | Primarily Layer 2 rollups |
| Fee market | Regular gas market | Separate blob gas market |
| Data storage | Transaction data can be permanent | Blob data is temporary |
| Introduced | Ethereum from the beginning | EIP-4844 |
| Main purpose | Pay for computation/resources | Make rollup data cheaper |
The important distinction is that blob gas does not replace Ethereum’s normal gas system.
Instead, Ethereum has a separate pricing mechanism for blob data.
Why Did Ethereum Introduce Blob Gas?
Before EIP-4844, Layer 2 networks commonly used Ethereum calldata to publish transaction data.
Calldata works, but storing large amounts of rollup data this way can be expensive.
Ethereum introduced blob transactions to provide a cheaper alternative.
This helps Layer 2 networks such as Base, Arbitrum, and Optimism publish transaction data at a lower cost.
The broader goal is to make Ethereum more scalable without requiring every piece of Layer 2 transaction data to remain permanently stored by every Ethereum node.
How Is the Blob Gas Price Determined?
Blob gas has its own EIP-1559-style fee mechanism.
Ethereum targets a certain amount of blob usage per block.
If blob demand is above the target, the blob base fee increases.
If demand is below the target, the blob base fee decreases.
This creates a market-based pricing system for blob space.
In simple terms:
High blob demand → higher blob gas price
Low blob demand → lower blob gas price
This mechanism helps Ethereum manage demand for its limited blob capacity.
What Is the Blob Base Fee?
The blob base fee is the minimum fee charged for blob gas under Ethereum’s blob fee market.
It operates separately from the normal Ethereum base fee.
This means Ethereum effectively has different fee markets for different resources.
For example:
Regular transactions → regular gas fees
Blob data → blob gas fees
This separation is important because a sudden increase in demand for blob space does not necessarily have the same effect as increased demand for ordinary Ethereum transaction execution.
Who Pays Blob Gas?
Layer 2 networks and the applications or users indirectly using those networks ultimately bear the cost of publishing rollup data.
For example, a rollup may batch thousands of transactions and publish the necessary data to Ethereum using blobs.
The rollup pays the associated blob costs.
Depending on the Layer 2’s fee structure, these costs can eventually be reflected in the fees users pay.
Does Blob Gas Make Ethereum Transactions Cheaper?
Not necessarily for Ethereum Layer 1 transactions.
Blob gas was primarily designed to reduce the cost of Layer 2 data publication.
Therefore, the biggest benefit is generally experienced by rollups and their users.
For example, if an L2 previously spent significant amounts of money publishing transaction data through calldata, moving that data into blobs can substantially reduce its data-availability costs.
Why Is Blob Gas Important for Layer 2?
Layer 2 rollups need to publish enough information to Ethereum so that their state and transactions can be verified.
Data availability is therefore a major component of rollup costs.
Blob data gives rollups a dedicated and cheaper way to publish this information.
This can help Layer 2 networks:
- Reduce operating costs
- Lower transaction fees
- Increase transaction capacity
- Support more users
- Scale Ethereum more efficiently
What Happens When Blob Demand Is High?
Blob space is limited.
If many rollups attempt to publish large amounts of data simultaneously, demand for blobs can increase.
When demand exceeds Ethereum’s target blob usage, the blob base fee rises.
This means blob gas is not always cheap.
Its price depends on how much demand exists for blob space at a particular time.
Is Blob Gas the Same as Ethereum Gas?
No.
This is one of the most important things to understand.
Ethereum uses regular gas to measure resources required for transaction execution, while blob gas is specifically associated with blob data.
You can therefore think of them as two separate resource and fee markets within Ethereum.
A transaction containing blobs can have both:
- A regular execution gas cost
- A blob gas cost
What Is EIP-4844?
EIP-4844 is the Ethereum improvement proposal that introduced blob transactions and blob gas.
It is also known as Proto-Danksharding.
The upgrade was included in Ethereum’s Dencun upgrade, which went live in March 2024.
EIP-4844 was designed as an intermediate step toward Ethereum’s longer-term danksharding roadmap.
Does Blob Data Stay on Ethereum Forever?
No.
One of the biggest differences between blob data and traditional blockchain data is that blobs are designed to be temporary.
Ethereum nodes retain blob data for a limited period rather than requiring it to remain permanently available on the blockchain.
This temporary design allows Ethereum to provide relatively inexpensive data availability without turning every blob into permanent blockchain storage.
Frequently Asked Questions About Blob Gas
What is blob gas in Ethereum?
Blob gas is the gas used to price the data stored in Ethereum blobs. It has a separate fee market from regular Ethereum gas and was introduced by EIP-4844.
Is blob gas cheaper than normal gas?
Blob gas is not directly comparable to normal gas because they price different resources. However, blob data was specifically designed to provide Layer 2 rollups with a cheaper way to publish data than traditional calldata.
Why does Ethereum need blob gas?
Ethereum needs blob gas to create a separate pricing mechanism for temporary blob data. This helps manage demand for blob space and allows rollups to publish large amounts of data more efficiently.
What is the difference between blob gas and gas?
Regular gas pays for Ethereum transaction execution and computational resources. Blob gas pays for the data availability provided by blobs.
Does blob gas affect Layer 2 fees?
Yes. Blob costs are part of the costs Layer 2 networks face when publishing data to Ethereum. Lower blob costs can therefore contribute to lower L2 transaction fees.
What happens when blob gas is high?
When demand for blob space increases, the blob base fee can increase. This makes publishing blobs more expensive for Layer 2 networks until demand falls or additional blob capacity becomes available.
Which Ethereum upgrade introduced blob gas?
Blob gas was introduced through EIP-4844 (Proto-Danksharding) as part of Ethereum’s Dencun upgrade in March 2024.
Can smart contracts access blob data?
Smart contracts cannot directly access the contents of blobs in the same way they access normal Ethereum contract storage or calldata. Blobs are primarily designed to provide temporary data availability for rollups.
Bottom Line
Blob gas is Ethereum’s separate fee mechanism for blob data. It was introduced with EIP-4844 to give Layer 2 rollups a cheaper and more scalable way to publish transaction data to Ethereum.
The simplest way to remember it is:
Regular gas pays for Ethereum computation. Blob gas pays for temporary blob data.
As Ethereum continues to scale through Layer 2 rollups and its broader danksharding roadmap, blob gas and blob capacity will remain important parts of Ethereum’s scaling architecture.
