Fees
How do network fees on Pivotal work?
Every Pivotal transaction consists of two costs: an L2 (execution) fee and an L1 (security) fee. The L2 fee is the cost to execute your transaction on the L2, and the L1 fee is the estimated cost to publish the transaction on the L1. Typically the L1 security fee is higher than the L2 execution fee.
The L1 fee will vary depending on the amount of transactions on the L1. If the timing of your transaction is flexible, you can save costs by submitting transactions during periods of lower gas on the L1 (for example, over the weekend)
Similarly, the L2 fee can increase and decrease depending on how many transactions are being submitted to the L2. This adjustment mechanism has the same implementation as the L1.\
Execution Gas Fee
A transaction's execution gas fee is exactly the same fee that you would pay for the same transaction on Ethereum. This fee is equal to the amount of gas used by the transaction multiplied by the gas price attached to the transaction.
Like Ethereum, Pivotal uses the EIP-1559 mechanism to set the base fee for transactions. The total price per unit gas that a transaction pays is the sum of the base fee and the optional additional priority fee.
Because Pivotal is EVM equivalent, the gas used by a transaction on Pivotal is exactly the same as the gas used by the same transaction on Ethereum. If a transaction costs 100,000 gas on Ethereum, it will cost 100,000 gas on Pivotal The only difference is that the gas price on Pivotal is much lower than the gas price on Ethereum so you'll end up paying much less in ETH.
For this component of the fee, you can estimate the total cost of a transaction using the same tools you would use to estimate the cost of a transaction on Ethereum. You can read more about how Ethereum's gas fees work over on Ethereum.org.
Base Fee
The base fee is the minimum price per unit of gas that a transaction must pay to be included in a block. Transactions must specify a maximum base fee higher than the block base fee to be included. The actual fee charged is the block base fee, even if the transaction specifies a higher maximum base fee.
The Pivotal base fee behaves exactly like the Ethereum base fee with a few small parameter changes to account for the much shorter block times on Pivotal. None of these parameters should significantly impact your application, but you can read more about each of these parameters on the OP Mainnet differences page. Read more about the base fee in the Ethereum.org documentation.
Priority Fee
Just like on Ethereum, Pivotal transactions can specify a priority fee. This priority fee is a price per unit of gas that is paid on top of the base fee. For example, if the block base fee is 1 gwei and the transaction specifies a priority fee of 1 gwei, the total price per unit of gas is 2 gwei. The priority fee is an optional component of the execution gas fee and can be set to 0.
The Pivotal sequencer will prioritise transactions with a higher priority fee and execute them before any transactions with a lower priority fee. If transaction speed is important to your application, you may want to set a higher priority fee to ensure that your transaction is included more quickly. The eth_maxPriorityFeePerGas RPC method can be used to estimate a priority fee that will get your transaction included quickly.
L1 Data Fee
The L1 Data Fee is the only part of the Pivotal transaction fee that differs from the Ethereum transaction fee. This fee arises from the fact that the transaction data for all Pivotal transactions is published to Ethereum. This guarantees that the transaction data is available for nodes to download and execute. The L1 Data Fee accounts for the cost to publish an OP Mainnet transaction to Ethereum and is primarily determined by the current base fee on Ethereum.
Mechanism
The L1 Data Fee is automatically charged for any transaction that is included in a Pivotal block. This fee is deducted directly from the address that sent the transaction. The exact amount paid depends on the estimated size of the transaction in bytes after compression, the current Ethereum gas price and/or blob gas price, and several small parameters.
The L1 Data Fee is most heavily influenced by the Ethereum base fee that is continuously and trustlessly relayed from Ethereum to Pivotal. With the Ecotone upgrade, the Ethereum blob base fee also gets relayed to Pivotal, and will become the most important factor for chains configured to use blobs instead of base fee. The base fee and blob base fee are updated on Pivotal for every Ethereum block, and each fluctuates at most by 12.5% between updates. As a result, short-term fluctuations of the L1 Data Fee are generally quite small and should not impact the average transaction.
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The L1 Data Fee is charged automatically. It is currently not possible to limit the maximum L1 Data Fee that a transaction is willing to pay. This is the result of limitations in existing Ethereum transaction formats and tradeoffs that the OP Stack makes to retain better EVM equivalence. Work is underway to improve this situation with the introduction of a new standardized transaction type. For now, you should be aware that the L1 Data Fee can fluctuate with the Ethereum gas price.
Formula
Bedrock
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The L1 Data Fee formula changed with the Ecotone upgrade. Refer to the Network Upgrade Overview for network upgrade activation timestamps for Pivotal Sepolia and Pivotal Mainnet.
Prior to the Ecotone upgrade, the L1 Data Fee is calculated based on the following parameters:
The signed transaction serialized according to the standard Ethereum transaction RLP encoding
The current Ethereum base fee (trustlessly relayed from Ethereum).
A fixed overhead cost for publishing a transaction (currently set to 188 gas).
A dynamic overhead cost which scales with the size of the transaction (currently set to 0.684).
The L1 Data Fee calculation first begins with counting the number of zero bytes and non-zero bytes in the transaction data. Each zero byte costs 4 gas and each non-zero byte costs 16 gas. This is the same way that Ethereum calculates the gas cost of transaction data.
After calculating the gas cost of the transaction data, the fixed and dynamic overhead values are applied.
Finally, the total L1 Data Fee is calculated by multiplying the total gas cost by the current Ethereum base fee.
Ecotone
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The L1 Data Fee formula changed with the Ecotone upgrade. Refer to the Network Upgrade Overview for network upgrade activation timestamps for OP Sepolia and OP Mainnet.
The pricing function changes with Ecotone upgrade because of the introduction of the option to post transaction batches to the L1 using blobs instead of through L1 calldata. This updated function uses the following parameters:
The signed transaction serialized according to the standard Ethereum transaction RLP encoding
The current Ethereum base fee and/or blob base fee (trustlessly relayed from Ethereum).
Two new scalar parameters that independently scale the base fee and blob base fee.
At the exact point of the Ecotone upgrade, the dynamic overhead parameter value is used to initialize the Ecotone base fee scalar, and blob base fee is set to 0. The overhead parameter from the previous function becomes ignored.
The Ecotone L1 Data Fee calculation begins with counting the number of zero bytes and non-zero bytes in the transaction data. Each zero byte costs 4 gas and each non-zero byte costs 16 gas. This value, when divided by 16, can be thought of as a rough estimate of the size of the transaction data after compression.
Next, the two scalars are applied to the base fee and blob base fee parameters to compute a weighted gas price multiplier.
The l1 data fee is then:
Recall that base_fee_scalar is set to dynamic_overhead and blob_base_fee_scalar is 0 immediately following the upgrade. Because the old overhead parameter becomes ignored, new L1 data prices will be (slightly, since overhead is typically a very small) lower than before the fork. Chain operators will likely want to retune the parameters appropriately after the fork, particularly if they plan on enabling blobs.
For additional details about fee calculation on Pivotal, please refer to the op-stack developer documentation.
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