Add components in matching ETH units
L2 execution cost equals L2 gas used × L2 gas price in gwei × 10⁻⁹ ETH. Total modeled cost equals that execution amount plus the entered L1 data fee in ETH. Multiply total ETH by the chosen ETH price to obtain quote-currency cost. Gas used is a quantity of computational units, while gas price is a charge per unit; entering a total fee in the gas-price field would produce an incorrect result.
Reconcile a hypothetical cost breakdown
Suppose L2 gas used is 200,000 and its price is 0.02 gwei. L2 execution costs 0.000004 ETH. With an entered L1 data fee of 0.00003 ETH, the modeled total is 0.000034 ETH. At a hypothetical ETH price of $2,000, that equals $0.068. In this example, reducing L2 gas use by half saves $0.004 while leaving the supplied data-fee component unchanged.
Match the model to the network fee breakdown
Networks can apply additional components or different pricing conventions, so this two-part total is complete only when it matches the scenario being analyzed. The tool does not infer compression ratios, estimate blob usage, or calculate a data fee from L1 gas price. Use an actual or explicitly assumed data-fee amount in ETH. Bridging charges, application fees, and token transfer value are excluded. Mixing values from different transactions or timestamps can make the combined total misleading.