// GLOSSARY -- WEB3 INFRASTRUCTURE

What is Blob Transaction (EIP-4844)?

1 min read Updated

A blob transaction (EIP-4844) is a new Ethereum transaction type that carries large data 'blobs' at reduced cost — designed specifically for Layer 2 rollups to post data to Ethereum more affordably.

WHY IT MATTERS

EIP-4844 (Proto-Danksharding) introduced blob-carrying transactions to Ethereum in March 2024. Blobs are large data attachments (~128KB each) with their own fee market, separate from regular gas. This dramatically reduced the cost of L2 data posting.

The impact was immediate: L2 transaction costs dropped by 10-100x. Posting a batch of thousands of transactions to Ethereum went from costing hundreds of dollars to single digits.

Blobs are temporary (pruned after ~18 days) — they provide data availability long enough for fraud proof windows but don't permanently bloat Ethereum's state. Full Danksharding will expand this further.

FREQUENTLY ASKED QUESTIONS

How much did EIP-4844 reduce L2 costs?
10-100x reduction in L2 transaction costs. A simple transfer on Base went from ~$0.10 to ~$0.001. The exact reduction depends on network conditions and rollup implementation.
What is a blob?
A ~128KB data attachment to a transaction with its own fee market (blob gas). Rollups use blobs to post compressed transaction data to Ethereum for data availability.
How long are blobs available?
~18 days after inclusion in a block. This is enough for optimistic rollup challenge periods (7 days). After 18 days, blobs are pruned — long-term archival is separate.

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