> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dynamic.xyz/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# estimateUserOperationGas

# 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

```javascript theme={"system"}
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

```javascript theme={"system"}
const estimatedGas = await estimateUserOperationGas({
  walletAccount,
  calls: [
    {
      to: "0x...",
      value: parseEther("0.1"),
    },
  ],
});

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

### Batch transaction

```javascript theme={"system"}
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

```javascript theme={"system"}
import {
  estimateUserOperationGas,
  sendUserOperation
} from "@dynamic-labs-sdk/zerodev";

const calls = [
  { 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

```javascript theme={"system"}
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:

```tsx theme={"system"}
import { estimateUserOperationGas, sendUserOperation } from '@dynamic-labs-sdk/zerodev';
import { isEvmWalletAccount } from '@dynamic-labs-sdk/evm';
import { useGetWalletAccounts } from '@dynamic-labs-sdk/react-hooks';
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 = [{ to: recipientAddress, value: parseEther('0.1'), data: '0x' as const }];

  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>
  );
}
```

## Related functions

* [sendUserOperation](/javascript/reference/zerodev/send-user-operation) - Send a user operation (single or batch)
* [canSponsorUserOperation](/javascript/reference/zerodev/can-sponsor-user-operation) - Check if operation can be sponsored
* [createKernelClientForWalletAccount](/javascript/reference/zerodev/create-kernel-client-for-wallet-account) - Create a ZeroDev Kernel client
* [isGasSponsorshipError](/javascript/reference/zerodev/is-gas-sponsorship-error) - Check if an error is a gas sponsorship error
* [Migration guide (v0.9)](/javascript/reference/zerodev/migration-v0.9) - Upgrading from the previous transaction API