# Gas

### klay\_feeHistory <a href="#klay_feehistory" id="klay_feehistory"></a>

Returns base fee per gas and transaction effective priority fee per gas history for the requested block range if available.

{% hint style="success" %}
**NOTE**: This API is effective after Klaytn v1.8.0
{% endhint %}

**Parameters**

| Name              | Type            | Description                                                                                                                                                                                              |
| ----------------- | --------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| blockCount        | QUANTITY        | Number of blocks in the requested range in hexadecimal. Between 1 (0x1) and 1024 (0x400) blocks can be requested in a single query. Less than requested may be returned if not all blocks are available. |
| lastBlock         | QUANTITY \| TAG | Highest numbered block of the requested range as block number or block tag.                                                                                                                              |
| rewardPercentiles | Array of FLOAT  | An array of floating point values between 0 and 100.                                                                                                                                                     |

**Return Value**

| Name          | Type              | Description                                                                                                                                                        |
| ------------- | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| oldestBlock   | QUANTITY          | Lowest numbered block of the returned range in hexadecimal.                                                                                                        |
| baseFeePerGas | Array of QUANTITY | An array of block base fees per gas. This includes the next block after the newest of the returned range, because this value can be derived from the newest block. |
| gasUsedRatio  | Array of FLOAT    | An array of the ratios of gas used per block. These are calculated as the ratio of gasUsed and gasLimit.                                                           |
| reward        | Array of QUANTITY | An array of effective priority fee per gas data points from a single block. All zeroes are returned if the block is empty.                                         |

**Example**

```shell
// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_feeHistory","params":["0x10", "latest", [0.1, 0.2, 0.3]],"id":1}' http://localhost:8551
// Result
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "oldestBlock": "0xa5b",
    "reward": [
      [ "0x0", "0x0", "0x0" ],
      ...
      [ "0x5d21dba00", "0x5d21dba00", "0x5d21dba00" ]
    ],
    "baseFeePerGas": [ "0x0", ..., "0x0" ],
    "gasUsedRatio": [ 0, ..., 0.0002963777000002964 ]
  }
}
```

### klay\_maxPriorityFeePerGas <a href="#klay_maxpriorityfeepergas" id="klay_maxpriorityfeepergas"></a>

Returns a suggestion for a gas tip cap for dynamic fee transactions in peb.

{% hint style="success" %}
**NOTE**: This API is effective after Klaytn v1.8.0
{% endhint %}

**Parameters**

None

**Return Value**

| Type     | Description                              |
| -------- | ---------------------------------------- |
| QUANTITY | Integer of the current gas price in peb. |

**Example**

```shell
// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_maxPriorityFeePerGas","params":[],"id":1}' http://localhost:8551
// Result
{
  "jsonrpc": "2.0",
  "id":1,
  "result": "0xAE9F7BCC00" // 250,000,000,000 peb = 250 Ston
}
```