Ethereum blobs are stored for approximately 18 days before Ethereum nodes can prune the blob data. More precisely, Ethereum’s protocol defines a minimum blob data retention period of 4096 epochs, which is roughly 18.2 days under normal Ethereum timing.
This temporary storage is one of the main differences between Ethereum blobs and calldata. Calldata becomes part of Ethereum’s historical transaction data, while blob contents are designed to be available only temporarily.
How Long Do Ethereum Blobs Last?
The commonly used answer is:
Ethereum blobs are available for about 18 days.
The protocol parameter is:
4096 epochs × 32 slots per epoch × 12 seconds per slot
That works out to approximately 18.2 days.
After this retention period, Ethereum nodes are allowed to delete—or prune—the actual blob data.
Why Are Ethereum Blobs Temporary?
Blobs were introduced through EIP-4844 (Proto-Danksharding) primarily to provide temporary data availability for Ethereum Layer 2 rollups.
Rollups need to publish transaction data to Ethereum so that the data can be verified and made available to network participants.
However, that data does not necessarily need to be stored by Ethereum nodes forever.
Instead, Ethereum provides a temporary availability window.
This approach helps prevent the blockchain’s permanent storage requirements from growing unnecessarily quickly.
What Happens After 18 Days?
After the blob retention period:
- The blob’s availability window expires.
- Nodes can prune the actual blob contents.
- The blob contents are no longer expected to be available from ordinary Ethereum nodes.
- The blockchain still retains the transaction and commitment information associated with the blob.
It’s important to understand that the blob itself isn’t simply erased from Ethereum’s entire history in every possible sense. The actual blob data can be pruned, while the associated transaction and cryptographic commitment remain part of the chain.
Are Ethereum Blobs Stored Permanently?
No, not as blob contents.
This is one of the defining characteristics of blobs.
| Data type | Storage |
|---|---|
| Ethereum calldata | Persistent transaction history |
| Ethereum blob contents | Temporary, ~18 days |
| Blob commitment/versioned hash | Remains associated with the blockchain |
This temporary design is what allows blobs to provide relatively inexpensive data availability.
Why Is 18 Days Enough?
Layer 2 rollups generally need enough time for network participants to obtain and verify the data associated with published batches.
The blob retention period gives participants a significant window to retrieve the data.
Afterward, the actual blob contents do not need to remain available from every Ethereum node indefinitely.
Rollups and other systems can also maintain their own copies of historical data when longer-term access is required.
Can You Retrieve an Old Ethereum Blob After 18 Days?
Not necessarily from a normal Ethereum node.
Once the retention period has passed, nodes are permitted to prune the blob contents.
However, other infrastructure may retain historical blob data.
For example, specialized archival services, rollup infrastructure, or independent data providers may keep copies for longer.
Therefore:
18 days = Ethereum’s protocol-level minimum retention window, not necessarily the maximum amount of time anyone anywhere can possess a copy of the data.
Ethereum Blobs vs Calldata
The difference becomes clearer when you compare the two:
Calldata
Calldata is included in an Ethereum transaction and becomes part of the blockchain’s historical transaction record.
Blob Data
Blob data is temporary and is designed to remain available for approximately 18 days.
This distinction was intentional.
Ethereum wanted to provide Layer 2 rollups with inexpensive data availability without making all of that data permanent blockchain history.
Frequently Asked Questions
How long are Ethereum blobs stored?
Ethereum’s protocol requires blob data to be retained for at least 4096 epochs, which is approximately 18.2 days under normal network timing.
Are Ethereum blobs deleted after 18 days?
Nodes are allowed to prune the blob contents after the retention period. This does not mean that every copy everywhere is automatically deleted.
Are Ethereum blob transactions permanent?
The transaction and its associated blockchain information remain part of Ethereum’s history, but the actual blob contents are temporary.
Can I access a blob after 18 days?
You may not be able to retrieve it from a standard Ethereum node after the retention period. A separate archival or data-availability service may have retained a copy.
Why don’t Ethereum blobs last forever?
Blobs were specifically designed as temporary data availability for Layer 2 rollups. Making them permanent would increase Ethereum’s long-term storage requirements.
What is the difference between blob storage and calldata storage?
Blob contents are temporary, while calldata is part of persistent Ethereum transaction history. This is one of the key reasons blobs can provide a more cost-efficient data-availability mechanism for rollups.
Ethereum blobs are designed to remain available for approximately 18 days. The exact protocol requirement is 4096 epochs, or roughly 18.2 days under Ethereum’s normal 12-second slot timing.
After that period, Ethereum nodes can prune the blob contents.
The key distinction is:
Calldata is persistent blockchain data; blob data is temporary data availability.
That temporary design is a fundamental part of EIP-4844 and Ethereum’s Layer 2 scaling strategy.
