# EstimateEnergy

Estimate the energy required for the successful execution of smart contract transactions or deploying a contract.

This method will use `30` [Compute Units](https://docs.validationcloud.io/v1/about/billing).

***

**Note:**

* This API is closed by default. To open this interface, the two configuration items `vm.estimateEnergy` and `vm.supportConstant` must be enabled in the node configuration file at the same time.
* The `wallet/triggerconstantcontract` API can be used to estimate the energy consumption value of calling most smart contracts on the chain, such as USDD, USDT, USDC, TUSD, etc. Meanwhile, Compared to the existing `wallet/triggerconstantcontract` API, `wallet/estimateEnergy` API will be more accurate in estimating the energy consumption of calling a small number of special contract. But for FullNode, enabling the `wallet/estimateEnergy` API is optional. So please pay attention that when developers call `wallet/estimateEnergy`, if the error message (this node does not support estimate energy) shows when calling the new API, it is recommended to continue using the `wallet/triggerconstantcontract` API to estimate energy consumption.
* `estimateenergy` will not generate an on-chain transaction, nor will it change the status of the current node.
* The `energy_required` field in the returned value is the energy estimated amount. Therefore, the `fee_limit` of the transaction can be set to `energy_required x energy unit price`.
* Parameter encoding and decoding example: [Parameter and return value encoding and decoding](https://developers.tron.network/docs/parameter-and-return-value-encoding-and-decoding)

## **Parameters**

* `owner_address` - String - Owner address that triggers the contract. If visible=true, use base58check format, otherwise use hex format. For constant call you can use the all-zero address.
* `contract_address` - String - Smart contract address. If visible=true, use base58check format, otherwise use hex format
* `function_selector` - String - Function call, must not be left blank
* `parameter` - String - Parameter encoding needs to be in accordance with the ABI rules, the rules are more complicated, users can use the ethers library to encode,For details, please refer to the document-Guide-Smart Contract-Best Practice-Parameter Encoding and Decoding.
* `data` - String - The data for interacting with smart contracts, including the contract function and parameters. You can choose to use this field, or you can choose to use function\_selector and parameter for contract interaction. When both of data and function\_selector exist, function\_selector is preferred
* `call_value` - int64 - Amount of TRX transferred to the contract with this transaction, the unit is sun
* `call_token_value` - int64 - Amount of TRC10 token transferred with this transaction
* `token_id` - int64 - TRC10 token id
* `visible` - boolean - Optional. Specifies whether the address is in Base58 format (default: false)

## **Returns**

| Field            | Type                 | Description                          |
| ---------------- | -------------------- | ------------------------------------ |
| result           | Return               | Run result                           |
| result.result    | bool                 | Is the estimate successful           |
| result.code      | response\_code(enum) | response code, an enum type          |
| result.message   | string               | Result message                       |
| energy\_required | int64                | Estimated energy to run the contract |

```json
// Result
{
  "result": {
    "result": true
  },
  "energy_required": 1082
}
```

{% tabs %}
{% tab title="mainnet" %}

```bash
curl https://mainnet.tron.validationcloud.io/v1/<YOUR_API_KEY_HERE>/wallet/estimateenergy \
    -X POST \
    -H "Content-Type: application/json" \
    -d '
{
  "owner_address": "TZ4UXDV5ZhNW7fb2AMSbgfAEZ7hWsnYS2g",
  "contract_address": "TG3XXyExBkPp9nzdajDZsozEu4BkaSJozs",
  "function_selector": "balanceOf(address)",
  "parameter": "000000000000000000000000a614f803b6fd780986a42c78ec9c7f77e6ded13c",
  "visible": true
}
'
```

{% endtab %}
{% endtabs %}