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

# Gas & fees

> Query gas price, priority fees, fee history, and estimate gas costs

## qc\_gasPrice

Returns the current gas price in wei.

```bash theme={null}
curl -X POST https://api.quantumapi.io/v1/rpc \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"qc_gasPrice","params":[],"id":1}'
```

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x3b9aca00"
}
```

***

## qc\_maxPriorityFeePerGas

Returns the suggested priority fee (tip) per gas for EIP-1559 transactions.

```bash theme={null}
curl -X POST https://api.quantumapi.io/v1/rpc \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"qc_maxPriorityFeePerGas","params":[],"id":1}'
```

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x3b9aca00"
}
```

***

## qc\_feeHistory

Returns historical gas fee data. Useful for estimating future fees.

| Parameter           | Type       | Description                                                            |
| ------------------- | ---------- | ---------------------------------------------------------------------- |
| `blockCount`        | `string`   | Number of blocks to look back (hex, max 1024)                          |
| `newestBlock`       | `string`   | Block number (hex) or tag                                              |
| `rewardPercentiles` | `number[]` | Percentiles to sample effective priority fees at (e.g. `[25, 50, 75]`) |

```bash theme={null}
curl -X POST https://api.quantumapi.io/v1/rpc \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "qc_feeHistory",
    "params": ["0x4", "latest", [25, 50, 75]],
    "id": 1
  }'
```

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "oldestBlock": "0x1a1",
    "baseFeePerGas": ["0x3b9aca00", "0x3b9aca00", "0x3b9aca00", "0x3b9aca00", "0x3b9aca00"],
    "gasUsedRatio": [0.021, 0.0, 0.0, 0.015],
    "reward": [
      ["0x3b9aca00", "0x3b9aca00", "0x3b9aca00"],
      ["0x0", "0x0", "0x0"],
      ["0x0", "0x0", "0x0"],
      ["0x3b9aca00", "0x3b9aca00", "0x3b9aca00"]
    ]
  }
}
```

***

## qc\_estimateGas

Estimates the gas needed to execute a transaction. The transaction is not sent.

| Parameter     | Type     | Description                            |
| ------------- | -------- | -------------------------------------- |
| `txObject`    | `object` | Transaction call object                |
| `blockNumber` | `string` | *(optional)* Block number (hex) or tag |

```bash theme={null}
curl -X POST https://api.quantumapi.io/v1/rpc \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "qc_estimateGas",
    "params": [{
      "from": "0xff81e5c74e14db5b4ee407d66b1b063c8f305c51",
      "to": "0x1234567890abcdef1234567890abcdef12345678",
      "value": "0xde0b6b3a7640000"
    }],
    "id": 1
  }'
```

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x5208"
}
```

<Tip>
  `0x5208` = 21000 gas, the base cost of a simple QUANTUM transfer.
</Tip>