Transaction fees on L2

The L2 execution fee

L2 execution fee is charged as tx.gasPrice * l2GasUsed (up to tx.gasLimit). The current L2 gas price is 0.001 gwei, however, this can vary depending on network congestion.

The L1 security fee

L1 security fee that pays for the cost of publishing the transaction on L1 (the cost of Ethereum equivalent security). It is deducted automatically from the user's ETH balance on Optimistic Ethereum. It is based on three factors that are multiplied together:

The gas price for L1 transactions (when the transaction was processed).
The gas used on L1 to publish the transaction. This is based on the transaction length, as well as the byte value (whether it is zero or a different value) for each byte.
The L1 fee scalar, which is at writing 1. You can see the current value in the contract. Take the value provided by the contract and divide by a million.