estimateUserOperationGas

Estimates the total gas cost for a user operation with one or more calls. Works for both single transactions and batch transactions. The estimation includes all gas components: call gas, verification gas, and pre-verification gas.

Usage

import { estimateUserOperationGas } from "@dynamic-labs-sdk/zerodev";
import { isEvmWalletAccount } from "@dynamic-labs-sdk/evm";
import { getPrimaryWalletAccount } from "@dynamic-labs-sdk/client";
import { parseEther, formatEther } from "viem";

const walletAccount = getPrimaryWalletAccount();

if (walletAccount && isEvmWalletAccount(walletAccount)) {
  const estimatedGas = await estimateUserOperationGas({
    walletAccount,
    calls: [
      {
        to: recipientAddress,
        value: parseEther("0.01"),
        data: "0x",
      },
    ],
  });

  if (estimatedGas) {
    console.log(`Estimated gas cost: ${formatEther(estimatedGas)} ETH`);
  } else {
    console.log("Failed to estimate gas");
  }
}

Parameters

Parameter	Type	Description
`calls`	`BatchCall[]`	Array of calls to execute (single or multiple)
`calls[].to`	`Hex`	The recipient address for this call
`calls[].value`	`bigint`	The value to send in wei for this call
`calls[].data`	`Hex` (optional)	The transaction data for this call
`walletAccount`	`EvmWalletAccount`	The wallet account that will execute the operation

Returns

Promise<bigint | null> - Returns the estimated gas cost in wei, or null if estimation fails. The gas estimate includes:

Call Gas Limit: Gas for executing the calls
Verification Gas Limit: Gas for validating the UserOperation
Pre-verification Gas: Fixed gas overhead

Examples

Single transaction

import { estimateUserOperationGas } from '@dynamic-labs-sdk/zerodev';
const estimatedGas = await estimateUserOperationGas({
  walletAccount,
  calls: [
    {
      to: "0x...",
      value: parseEther("0.1"),
    },
  ],
});

if (estimatedGas) {
  console.log(`Gas estimate: ${estimatedGas} wei`);
}

Batch transaction

import { estimateUserOperationGas } from '@dynamic-labs-sdk/zerodev';
const estimatedGas = await estimateUserOperationGas({
  walletAccount,
  calls: [
    { to: "0xRecipient1...", value: parseEther("0.1") },
    { to: "0xRecipient2...", value: parseEther("0.2") },
    { to: "0xRecipient3...", value: parseEther("0.3") },
  ],
});

if (estimatedGas) {
  console.log(`Batch gas estimate: ${formatEther(estimatedGas)} ETH`);
}

Estimate before sending

import {
  estimateUserOperationGas,
  sendUserOperation
} from "@dynamic-labs-sdk/zerodev";
import type { BatchCall } from "@dynamic-labs-sdk/zerodev";

const calls: BatchCall[] = [
  { to: "0x...", value: parseEther("0.1") },
  { to: "0x...", value: parseEther("0.2") },
];

// Estimate gas first
const estimatedGas = await estimateUserOperationGas({
  walletAccount,
  calls,
});

if (estimatedGas) {
  const gasInEth = formatEther(estimatedGas);
  console.log(`This operation will cost approximately ${gasInEth} ETH`);

  // User confirms, then send
  const receipt = await sendUserOperation({
    walletAccount,
    calls,
  });
  console.log("Transaction sent:", receipt.userOpHash);
}

With contract interaction

import { estimateUserOperationGas } from "@dynamic-labs-sdk/zerodev";
import { encodeFunctionData } from "viem";

const estimatedGas = await estimateUserOperationGas({
  walletAccount,
  calls: [
    {
      to: tokenAddress,
      value: 0n,
      data: encodeFunctionData({
        abi: erc20Abi,
        functionName: "transfer",
        args: [recipientAddress, parseEther("100")],
      }),
    },
  ],
});

Notes

Gas estimation creates a kernel client without sponsorship to get accurate unsponsored gas costs
Returns null if estimation fails (e.g., insufficient funds, invalid call)
Batch transactions may save gas compared to individual transactions due to shared validation costs
The actual gas used may differ slightly from the estimate

React

Show the gas estimate to the user before they confirm the transaction:

import { estimateUserOperationGas, sendUserOperation } from '@dynamic-labs-sdk/zerodev';
import { isEvmWalletAccount } from '@dynamic-labs-sdk/evm';
import { useGetWalletAccounts } from '@dynamic-labs-sdk/react-hooks';
import type { BatchCall } from '@dynamic-labs-sdk/zerodev';
import { useState } from 'react';
import { parseEther, formatEther } from 'viem';

function GasEstimateFlow({ recipientAddress }) {
  const { data: walletAccounts = [] } = useGetWalletAccounts();
  const walletAccount = walletAccounts.find(isEvmWalletAccount);
  const [gasEstimate, setGasEstimate] = useState('');
  const [confirmed, setConfirmed] = useState(false);

  const calls: BatchCall[] = [
    { to: recipientAddress, value: parseEther('0.1'), data: '0x' },
  ];

  const handleEstimate = async () => {
    if (!walletAccount) return;
    const gas = await estimateUserOperationGas({ walletAccount, calls });
    if (gas) setGasEstimate(formatEther(gas));
  };

  const handleSend = async () => {
    if (!walletAccount) return;
    await sendUserOperation({ walletAccount, calls });
    setConfirmed(true);
  };

  return (
    <div>
      <button onClick={handleEstimate} disabled={!walletAccount}>Estimate Gas</button>
      {gasEstimate && (
        <div>
          <p>Estimated gas: {gasEstimate} ETH</p>
          <button onClick={handleSend}>Confirm & Send</button>
        </div>
      )}
      {confirmed && <p>Transaction sent!</p>}
    </div>
  );
}

sendUserOperation - Send a user operation (single or batch)
canSponsorUserOperation - Check if operation can be sponsored
createKernelClientForWalletAccount - Create a ZeroDev Kernel client
isGasSponsorshipError - Check if an error is a gas sponsorship error
Migration guide (v0.9) - Upgrading from the previous transaction API

​estimateUserOperationGas

​Usage

​Parameters

​Returns

​Examples

​Single transaction

​Batch transaction

​Estimate before sending

​With contract interaction

​Notes

​React

​Related functions