calculateFeeForUserOperation

Calculate the fee for a ZeroDev user operation from known gas values

Calculates the total fee for a ZeroDev user operation given its gas limits and max fee per gas. Returns fee data in native units (wei), human-readable format (ETH), and optionally USD.

Unlike estimateUserOperationGas, this function is synchronous and does not make any network calls — it computes the fee from gas values you already have (e.g., after calling estimateUserOperationGas or building a user operation manually).

Installation

npm install @dynamic-labs-sdk/zerodev

Usage

import { calculateFeeForUserOperation, estimateUserOperationGas } from '@dynamic-labs-sdk/zerodev';
import { getNetworksData } from '@dynamic-labs-sdk/client';
import { parseGwei } from 'viem';

const networks = getNetworksData();
const networkData = networks.find((n) => n.networkId === '1');

const feeData = calculateFeeForUserOperation({
  userOperationData: {
    callGasLimit: 100_000n,
    verificationGasLimit: 50_000n,
    preVerificationGas: 21_000n,
    maxFeePerGas: parseGwei('50'),
  },
  networkData,
});

console.log(`Estimated fee: ${feeData.humanReadableAmount} ETH`);

Parameters

Parameter	Type	Description
userOperationData	object	Gas values for the user operation
userOperationData.callGasLimit	bigint	Gas limit for the call phase
userOperationData.verificationGasLimit	bigint	Gas limit for the verification phase
userOperationData.preVerificationGas	bigint	Fixed pre-verification gas overhead
userOperationData.maxFeePerGas	bigint	Maximum fee per gas unit in wei
networkData	NetworkData	Network configuration. Get this from getNetworksData()
nativeTokenPriceUsd	number (optional)	USD price of the native token, used to calculate usdAmount

Returns

EvmTransactionFeeData (synchronous — not a Promise):

Field	Type	Description
nativeAmount	bigint	Total fee in wei: (callGasLimit + verificationGasLimit + preVerificationGas) × maxFeePerGas
humanReadableAmount	string	Fee in ETH, formatted for display
usdAmount	string (optional)	Fee in USD. Present only when nativeTokenPriceUsd is provided
gasEstimate	bigint	Total gas units: callGasLimit + verificationGasLimit + preVerificationGas
maxFeePerGas	bigint	The maxFeePerGas value passed in

Examples

Display fee before sending

import {
  calculateFeeForUserOperation,
  sendUserOperation,
} from '@dynamic-labs-sdk/zerodev';

const feeData = calculateFeeForUserOperation({
  userOperationData: {
    callGasLimit: 100_000n,
    verificationGasLimit: 50_000n,
    preVerificationGas: 21_000n,
    maxFeePerGas: parseGwei('30'),
  },
  networkData,
});

console.log(`This operation will cost ~${feeData.humanReadableAmount} ETH`);

const receipt = await sendUserOperation({ walletAccount, calls });

With USD conversion

const ETH_PRICE_USD = 3200;

const feeData = calculateFeeForUserOperation({
  userOperationData: {
    callGasLimit: 100_000n,
    verificationGasLimit: 50_000n,
    preVerificationGas: 21_000n,
    maxFeePerGas: parseGwei('50'),
  },
  networkData,
  nativeTokenPriceUsd: ETH_PRICE_USD,
});

console.log(`Fee: ${feeData.humanReadableAmount} ETH ≈ $${feeData.usdAmount}`);

Error handling

import { FeeEstimationFailedError } from '@dynamic-labs-sdk/client';

try {
  const feeData = calculateFeeForUserOperation({ userOperationData, networkData });
} catch (error) {
  if (error instanceof FeeEstimationFailedError) {
    console.error('Fee calculation failed:', error.message);
  }
}

Related functions

• estimateUserOperationGas - Estimate gas cost for a user operation (makes network calls)
• simulateZerodevUserOperation - Full simulation with asset diffs and security validation
• sendUserOperation - Send a user operation
• calculateEvmTransactionFee - Fee estimation for standard EVM transactions
• getNetworksData - Get network configuration objects