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

# eth_estimateGas

> Estimates the gas required for a transaction. Use pending to estimate against pre-confirmed state.

Returns an estimate of how much gas is required to execute a transaction. The estimate may be larger than the gas actually used at execution time.

<Tip>
  **Flashblocks:** Query `https://mainnet.base.org` with `"pending"` to estimate gas against the current pre-confirmed state, useful when a transaction depends on a prior pre-confirmed one.
</Tip>

## Parameters

<ParamField body="transaction" type="object" required>
  The transaction object to estimate gas for.

  <Expandable title="Transaction fields">
    <ParamField body="from" type="string">
      Address the transaction is sent from. Optional.
    </ParamField>

    <ParamField body="to" type="string">
      Address the transaction is sent to. Optional for contract deployments.
    </ParamField>

    <ParamField body="gas" type="string">
      Gas limit. Optional; a high default is used if omitted.
    </ParamField>

    <ParamField body="gasPrice" type="string">
      Gas price in wei for legacy transactions. Optional.
    </ParamField>

    <ParamField body="maxFeePerGas" type="string">
      EIP-1559 maximum total fee per gas. Optional.
    </ParamField>

    <ParamField body="maxPriorityFeePerGas" type="string">
      EIP-1559 maximum priority fee per gas. Optional.
    </ParamField>

    <ParamField body="value" type="string">
      Value to transfer in wei. Optional.
    </ParamField>

    <ParamField body="data" type="string">
      ABI-encoded call data. Optional.
    </ParamField>
  </Expandable>
</ParamField>

<ParamField body="block" type="string">
  Block to estimate against. Optional; defaults to `"latest"`. Use `"pending"` to estimate against pre-confirmed state.
</ParamField>

## Returns

<ResponseField name="result" type="string">
  The estimated gas amount as a hexadecimal integer.
</ResponseField>

## Error Codes

| Code     | Message            | Description                                                                       |
| -------- | ------------------ | --------------------------------------------------------------------------------- |
| `-32000` | execution reverted | The transaction would revert. The error `data` field may contain a revert reason. |

## Example

<CodeGroup>
  ```bash Standard theme={null}
  curl https://mainnet.base.org \
    -X POST \
    -H "Content-Type: application/json" \
    -d '{
      "jsonrpc": "2.0",
      "method": "eth_estimateGas",
      "params": [{
        "from": "0xd3CdA913deB6f4967b2Ef66ae97DE114a83bcc01",
        "to": "0x4200000000000000000000000000000000000006",
        "value": "0x2c68af0bb14000"
      }],
      "id": 1
    }'
  ```

  ```bash Flashblocks (pending state) theme={null}
  curl https://mainnet.base.org \
    -X POST \
    -H "Content-Type: application/json" \
    -d '{
      "jsonrpc": "2.0",
      "method": "eth_estimateGas",
      "params": [{
        "from": "0xd3CdA913deB6f4967b2Ef66ae97DE114a83bcc01",
        "to": "0x4200000000000000000000000000000000000006",
        "value": "0x2c68af0bb14000"
      }, "pending"],
      "id": 1
    }'
  ```

  ```json Response theme={null}
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x5208"
  }
  ```
</CodeGroup>