Optimism Documentation

This page catalogues the fee-related parameters a chain operator can set on the SystemConfig contract, from the Jovian hardfork onward. For how fees are calculated and charged, see transaction fees on OP Mainnet. For when and how to adjust these parameters, see the fee tuning guide.

Only the SystemConfig owner can call the setter methods listed below.

Fee formulas

On an OP Stack chain a transaction’s Total Fee is made of three main components: Total Fee = L2 Fee + L1 Fee + Operator Fee

Component	Formula
L2 fee	`gasUsed * (baseFee + priorityFee)`
L1 fee	`estimatedSizeScaled * l1FeeScaled / 1e12` (see below)
Operator fee	`(gasUsed * operatorFeeScalar * 100) + operatorFeeConstant`

The L1 fee charges for posting L2 data to L1, based on the transaction’s estimated compressed (FastLZ) size:

l1FeeScaled =
  baseFeeScalar * 16 * l1BaseFee +
  blobBaseFeeScalar * l1BlobBaseFee

estimatedSizeScaled =
  max(
    minTransactionSize * 1e6,
    intercept + fastlzCoef * fastlzSize
  )

l1Fee = estimatedSizeScaled * l1FeeScaled / 1e12

Pre-Jovian (Isthmus) operator fee formula: operatorFee = (gasUsed * operatorFeeScalar / 1e6) + operatorFeeConstant

Parameters

All parameters live on the SystemConfig contract on L1 (see the ISystemConfig interface). Each getter below is a view method with the same name as the parameter.

Parameter	Type	What it controls	Setter	OP Mainnet value
`eip1559Denominator`	`uint32`	EIP-1559 max-change denominator: appears in the denominator of the per-block base fee delta. Lower = faster base fee response, more volatility.	`setEIP1559Params(uint32,uint32)`	`250`
`eip1559Elasticity`	`uint32`	Elasticity multiplier: sets the gas target relative to the gas limit (`gas_target = gasLimit / elasticity`). Larger elasticity = smaller target, so base fee increases sooner under load.	`setEIP1559Params(uint32,uint32)`	`2`
`gasLimit`	`uint64`	Maximum gas per block. Lower limit = less supply per block, making base fees more sensitive to demand.	`setGasLimit(uint64)`	`40,000,000`
`minBaseFee`	`uint64`	Minimum floor on the base fee, in wei (can be 0). See setting the minimum base fee.	`setMinBaseFee(uint64)`	`0`
`basefeeScalar`	`uint32`	Scales the `l1BaseFee` (per-byte) contribution to the L1 data fee.	`setGasConfigEcotone(uint32,uint32)`	`5227`
`blobbasefeeScalar`	`uint32`	Scales the `l1BlobBaseFee` (per-blob) contribution to the L1 data fee.	`setGasConfigEcotone(uint32,uint32)`	`1014213`
`operatorFeeScalar`	`uint32`	Per-gas operator margin. See setting the operator fee.	`setOperatorFeeScalars(uint32,uint64)`	`0`
`operatorFeeConstant`	`uint64`	Flat per-transaction operator fee, in wei.	`setOperatorFeeScalars(uint32,uint64)`	`0`
`daFootprintGasScalar`	`uint16`	Scales estimated DA usage to the gas dimension to limit DA-heavy blocks. See how the DA footprint block limit works.	`setDAFootprintGasScalar(uint16)`	`0` (treated as `400`)

Any non-zero operator fee makes the chain configuration non-standard.
A daFootprintGasScalar of 0 is treated as the default of 400; set it to 1 to effectively disable the DA footprint limit.

The OP Mainnet values can be verified against the OP Mainnet SystemConfig contract on Etherscan.

Fee vault recipients

Fees are gathered in dedicated contract fee vaults. See the fee vault operations guide for how to manage and withdraw from these vaults.

Fee component	Recipient vault
`baseFee`	`BaseFeeVault`
`priorityFee`	`SequencerFeeVault`
`l1Fee`	`L1FeeVault`
`operatorFee`	`OperatorFeeVault`

Reading current values

Each parameter has a getter with the same name on the SystemConfig contract:

export L1_RPC=<L1_RPC>
export SYSTEM_CONFIG=<SYSTEM_CONFIG_ADDRESS>

cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "eip1559Denominator()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "eip1559Elasticity()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "gasLimit()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "minBaseFee()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "basefeeScalar()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "blobbasefeeScalar()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "operatorFeeScalar()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "operatorFeeConstant()"
cast call --rpc-url $L1_RPC $SYSTEM_CONFIG "daFootprintGasScalar()"

Fee parameters

Fee formulas

Parameters

Fee vault recipients

Reading current values

References

​Fee formulas

​Parameters

​Fee vault recipients

​Reading current values

​References

Fee formulas

Parameters

Fee vault recipients

Reading current values

References