Library · Crypto, word by word · Inside Ethereum
What is a blob?
A blob is a large chunk of data, about 128 KB, that can be attached to an Ethereum block through a special transaction type. Layer 2 rollups use blobs to publish their transaction data cheaply, and the network deletes the data after about 18 days.
What it means for you
Blobs are a large part of why layer 2 networks can charge low fees, but blob space has its own price that rises with demand, so layer 2 fees can climb when many rollups compete for it. Because blob data is pruned after roughly 18 days, it is not a permanent on-chain record.
How it works
EIP-4844, known as proto-danksharding and live since the Dencun upgrade in March 2024, added blob-carrying transactions. Each blob holds 4,096 field elements of 32 bytes, 128 KiB in all. The EVM cannot read a blob's contents, only a versioned hash of its KZG commitment, which lets anyone check that published data matches. Blobs are priced in a separate blob gas market with its own fee. Consensus nodes keep them for 4,096 epochs, about 18 days, long enough for rollup participants to retrieve the data.
Sources: EIP-4844: Shard blob transactions, ethereum.org: Danksharding · checked 4 October 2026
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