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@receipts:block.blobBaseFee

Blob base fee in wei: the live value with no arguments, or the EIP-4844 value of a sealed block computed from its excess blob gas (blocks predating EIP-4844 error).

On-chain (@receipts:block.blobBaseFee!): Reads the block being written, and takes no arguments.

⚗️ Experimental — available at next.evmcrispr.com.

Returns: number

@receipts:block.blobBaseFee(block? chain?)
NameTypeDescription
[block]number | stringBlock number or tag (default: latest)
[chain]chainChain to look on (default: current chain)
# Read the blob base fee a sealed block charged
set $blobfee @receipts:block.blobBaseFee(19529728 mainnet)

The off-chain face has two paths:

  • No block argument: the live value straight from the node, via the eth_blobBaseFee RPC.
  • A block number or tag: the EIP-4844 value of that sealed block, recomputed from its header as fake_exponential(MIN_BLOB_BASE_FEE, excessBlobGas, BLOB_BASE_FEE_UPDATE_FRACTION), i.e. fake_exponential(1, excessBlobGas, 3338477): an integer-only Taylor expansion of e**(excessBlobGas / 3338477) wei. Blocks sealed before EIP-4844 carry no excess blob gas and error clearly.

With ! and no arguments the read happens on-chain at assertion time: the blob base fee of the block being written (the BLOBBASEFEE opcode).