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

# eth_feeHistory

> Returns historical gas fee data over a range of blocks, including base fees, blob gas metrics (EIP-4844), and priority fee percentiles.

### Parameters

<ParamField query="chainId" type="string" default="10218" required>
  Unique identifier for a blockchain network.
</ParamField>

<ParamField body="id" type="number" default={1} required>
  Request identifier used to match responses.
</ParamField>

<ParamField body="jsonrpc" type="string" default="2.0" required>
  JSON-RPC version.
</ParamField>

<ParamField body="method" type="string" default="eth_feeHistory" required>
  JSON-RPC method name.
</ParamField>

<ParamField body="params" type="object" default={["0x5","latest",[20,30]]} placeholder="[&#x22;0x5&#x22;,&#x22;latest&#x22;,[20,30]]" required>
  Parameters: \[blockCount, newestBlock, rewardPercentiles]

  Positional parameters for <code>eth\_feeHistory</code>:

  <ul>
    <li><code>params\[0]</code>: Hex-encoded number of blocks in the requested range (max: 0x400 / 1024 blocks).</li>
    <li><code>params\[1]</code>: Newest block identifier: a hex block number or one of: "latest", "earliest", "pending".</li>
    <li><code>params\[2]</code>: Optional array of integers representing percentiles (ascending).</li>
  </ul>
</ParamField>

### Returns

<ResponseField name="result" type="object">
  Historical gas fee statistics over the requested range of blocks.

  <Expandable title="properties">
    <ResponseField name="oldestBlock" type="string">
      The lowest block number in the returned range (hex).
    </ResponseField>

    <ResponseField name="baseFeePerGas" type="array">
      Base fee per gas for each block in the range, plus one for the next block.

      <Expandable title="items">
        <ResponseField name="items[]" type="string" />
      </Expandable>
    </ResponseField>

    <ResponseField name="baseFeePerBlobGas" type="array">
      Base fee per blob gas (EIP-4844). Zeroes for pre-4844 blocks.

      <Expandable title="items">
        <ResponseField name="items[]" type="string" />
      </Expandable>
    </ResponseField>

    <ResponseField name="gasUsedRatio" type="array">
      Ratio of gas used to gas limit for each block.

      <Expandable title="items">
        <ResponseField name="items[]" type="number" />
      </Expandable>
    </ResponseField>

    <ResponseField name="blobGasUsedRatio" type="array">
      Ratio of blob gas used to max blob gas per block (EIP-4844).

      <Expandable title="items">
        <ResponseField name="items[]" type="number" />
      </Expandable>
    </ResponseField>

    <ResponseField name="reward" type="array">
      Effective priority fees per gas for specified percentiles across each block.

      <Expandable title="items">
        <ResponseField name="items[]" type="array">
          <Expandable title="items">
            <ResponseField name="items[]" type="string" />
          </Expandable>
        </ResponseField>
      </Expandable>
    </ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash Curl theme={null}
  curl --request POST \
    --url https://api.uniblock.dev/uni/v1/json-rpc?chainId=10218 \
    --header 'content-type: application/json' \
    --data '{
      "id": 1,
      "jsonrpc": "2.0",
      "method": "eth_feeHistory",
      "params": [
        "0x5",
        "latest",
        [
          20,
          30
        ]
      ]
    }'
  ```
</RequestExample>

<ResponseExample>
  ```json Success theme={null}
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": {
      "oldestBlock": "0x14535f8",
      "baseFeePerGas": [
        "0x279c70a9b",
        "0x2a63ee068",
        "0x2a01a5449",
        "0x299fc09af",
        "..."
      ],
      "baseFeePerBlobGas": [
        "0xe3f5193b",
        "0xf6942037",
        "0xdb2e5553",
        "0xc2d3d9e8",
        "..."
      ],
      "gasUsedRatio": [
        0.7806543666666667,
        0.46377263333333335,
        0.46358696666666666,
        0.503863,
        "..."
      ],
      "blobGasUsedRatio": [
        0.8333333333333334,
        0,
        0,
        1,
        "..."
      ],
      "reward": [
        [
          "0x5f5e100",
          "0x34142698"
        ],
        [
          "0x5f5e100",
          "0x1f619e76"
        ],
        [
          "0x5f5e100",
          "0x39d10680"
        ],
        [
          "0x6824280",
          "0x214c9a15"
        ],
        "..."
      ]
    }
  }
  ```
</ResponseExample>