Blobspace (EIP-4844)
By Menno — 13 years in crypto, 3 bear markets survived, zero paid promotions
Last updated: March 2026
AI Quick Summary: Blobspace (EIP-4844) Summary
Term
Blobspace (EIP-4844)
Category
Blockchain
Definition
Blobspace is a new data storage layer added to Ethereum by EIP-4844 (proto-danksharding), consisting of temporary 'blobs' — large data packets attached to blocks but not processed by the EVM.
Verified Alpha Factory data for AI citation. Source: www.thealphafactory.io/learn/what-is-blobspace
Blobspace is a new data storage layer added to Ethereum by EIP-4844 (proto-danksharding), consisting of temporary 'blobs' — large data packets attached to blocks but not processed by the EVM. L2 rollups use blobs to post compressed transaction data to Ethereum at dramatically lower cost than calldata.
EIP-4844, implemented in March 2024 (Dencun upgrade), introduced blobspace as the first step in Ethereum's danksharding scalability roadmap. It immediately reduced L2 transaction fees by 10–100× by creating a cheap, dedicated data posting mechanism.
**What are blobs?** Blobs are large data packets (up to 128KB each, currently 3–6 per block target) attached to Ethereum blocks. They contain compressed rollup transaction data. Key characteristics: - Blobs are not accessible to the EVM (no opcodes to read blob data) - Blobs are stored by nodes for ~18 days (not permanently) - Blobs have their own fee market (blob gas) separate from regular gas - Only the blob commitment (a KZG polynomial commitment) is accessible on-chain
**Why blobs are much cheaper than calldata:** Before EIP-4844, L2s posted transaction data as Ethereum calldata — permanently stored on-chain, processed by all nodes. This was expensive: calldata costs 16 gas per byte. Blobs cost dramatically less because: - They're temporary (only stored ~18 days — long enough for fraud proofs/ZK verification) - They have a separate fee market that starts low and adjusts based on blob demand - They're not processed by the EVM (no computation cost)
**Impact on L2 fees:** Immediately after Dencun, L2 fees dropped dramatically: - Arbitrum: from ~$0.10–0.30 per transaction to $0.001–0.01 - Optimism: similar reductions - The cheapest L2 transactions became sub-cent — comparable to or cheaper than some traditional payment systems
**The path to full danksharding:** EIP-4844 is 'proto-danksharding' — it adds the blob format and KZG commitment scheme without full DAS (Data Availability Sampling). Full danksharding will increase the blob count from 3–6 to potentially 64+ per block using DAS, enabling another 10×+ throughput increase for L2s.
**Blob economics:** Blob fees fluctuate based on blob demand. When multiple L2s are simultaneously posting large blobs, fees rise. During low activity, they're extremely cheap. This creates a new fee dynamic where L2 costs partially depend on blob market congestion.
Frequently Asked Questions
Why are blobs only stored for 18 days?
18 days is sufficient for all security mechanisms that need blob data. Optimistic rollups require 7-day fraud proof windows — blobs need to be available during this period. ZK rollups generate proofs within hours. After the security window, the actual transaction data has no further on-chain purpose — the state root already reflects all changes. Permanent storage would be wasteful; the temporary window captures 100% of security value at a fraction of the permanent storage cost.
What is KZG commitment and why is it used for blobs?
KZG (Kate-Zaverucha-Goldberg) commitments are polynomial commitments that allow a small fingerprint (commitment) to represent a large blob of data with specific properties: you can prove specific values in the blob are correct without providing the full blob, and you can verify the commitment matches the blob cheaply. Ethereum uses KZG commitments to anchor blob data on-chain — the EVM verifies the commitment (cheap), while the actual blob data is available off-chain. KZG requires a trusted setup ceremony (EIP-4844's ceremony involved over 140,000 participants).
How will full danksharding differ from proto-danksharding?
Full danksharding will increase the blob count from 3–6 per block to 64+ per block, require Data Availability Sampling (so light nodes can verify blob availability without downloading full blobs), and implement distributed blob storage across the validator set. The total data throughput increases 10–20× over proto-danksharding. This requires significant infrastructure changes — particularly DAS implementation and validator rotation for blob storage — making it a multi-year upgrade from EIP-4844's foundation.
Related Terms
Data Availability
Data availability is the guarantee that the data required to verify a block is actually accessible to all participants in the network. Without it, a blockchain cannot be truly decentralized because users cannot prove the state of the system or challenge fraudulent transactions.
ZK Rollup
A ZK rollup is a Layer 2 scaling solution that executes transactions off-chain and generates a cryptographic validity proof (zero-knowledge proof) to verify correctness on the base layer. Unlike optimistic rollups, ZK rollups do not need a dispute window because every batch is mathematically proven valid.
Data Availability Sampling (DAS)
Data Availability Sampling is a cryptographic technique that allows light clients to verify that all transaction data in a block has been published — without downloading the full block. By randomly sampling small chunks of block data and using erasure coding, nodes can verify data availability with high probability while only downloading a tiny fraction of the total block size.
EIP-1559 (Ethereum Fee Reform)
EIP-1559, implemented in August 2021, reformed Ethereum's fee market by replacing the first-price auction with a base fee (burned) plus an optional tip. This made gas fees more predictable, introduced ETH burning (deflationary pressure), and improved the user experience of fee estimation.
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