> ## 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.

# kaia_feeHistory

> Returns historical base fee and priority fee percentile data for recent blocks.

### Parameters

<ParamField query="chainId" type="string" default="1001" 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="kaia_feeHistory" required>
  JSON-RPC method name.
</ParamField>

<ParamField body="params" type="object" default={["0x5",0,[10,50,90]]} placeholder="[&#x22;0x5&#x22;,0,[10,50,90]]" required>
  Parameters: \[blockCount, newestBlock, rewardPercentiles].

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

  <ul>
    <li><code>params\[0]</code>: Hex-encoded number of blocks in the requested range (max 1024).</li>
    <li><code>params\[1]</code>: Block number where this transaction was included. Null when pending.</li>
    <li><code>params\[2]</code>: Percentiles of priority fees to include in the response (0-100).</li>
  </ul>
</ParamField>

### Returns

<ResponseField name="result" type="object">
  Base fee history for the requested block range.

  <Expandable title="properties">
    <ResponseField name="oldestBlock" type="string">
      Hex block number of the first block in the range.
    </ResponseField>

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

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

    <ResponseField name="gasUsedRatio" type="array">
      Gas used ratio for each returned block.

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

    <ResponseField name="reward" type="array">
      Priority fee rewards per percentile requested (omitted if no percentages were supplied).

      <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=1001 \
    --header 'content-type: application/json' \
    --data '{
      "id": 1,
      "jsonrpc": "2.0",
      "method": "kaia_feeHistory",
      "params": [
        "0x5",
        0,
        [
          10,
          50,
          90
        ]
      ]
    }'
  ```
</RequestExample>

<ResponseExample>
  ```json Success theme={null}
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": {}
  }
  ```
</ResponseExample>