# estimateContractGas

Estimates the gas required to successfully execute a contract write function call.

Internally, `estimateContractGas` uses a [Public Client](/docs/clients/public) to call the [`estimateGas` action](/docs/actions/public/estimateGas) with [ABI-encoded `data`](/docs/contract/encodeFunctionData).

## Usage

Below is a very basic example of how to estimate gas (with no arguments).

The `mint` function accepts no arguments, and returns a token ID.

:::code-group
```ts [example.ts]
import { account, publicClient } from './config'
import { wagmiAbi } from './abi'

const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  account,
})
// 69420n
```

```ts [abi.ts]
export const wagmiAbi = [
  ...
  {
    inputs: [],
    name: "mint",
    outputs: [{ name: "", type: "uint32" }],
    stateMutability: "view",
    type: "function",
  },
  ...
] as const;
```

```ts [config.ts]
import { createPublicClient, http } from 'viem'
import { privateKeyToAccount } from 'viem/accounts'
import { mainnet } from 'viem/chains'

// JSON-RPC Account
export const account = '0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266'
// Local Account
export const account = privateKeyToAccount(...)

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})
```
:::

### Passing Arguments

If your function requires argument(s), you can pass them through with the `args` attribute.

TypeScript types for `args` will be inferred from the function name & ABI, to guard you from inserting the wrong values.

For example, the `mint` function name below requires a **tokenId** argument, and it is typed as `[number]`.

:::code-group
```ts [example.ts] {8}
import { account, publicClient } from './config'
import { wagmiAbi } from './abi'

const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  account,
})
// 69420n
```

```ts [abi.ts]
export const wagmiAbi = [
  ...
  {
    inputs: [{ name: "owner", type: "uint32" }],
    name: "mint",
    outputs: [{ name: "", type: "uint32" }],
    stateMutability: "nonpayable",
    type: "function",
  },
  ...
] as const;
```

```ts [config.ts]
import { createPublicClient, http } from 'viem'
import { privateKeyToAccount } from 'viem/accounts'
import { mainnet } from 'viem/chains'

// JSON-RPC Account
export const account = '0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266'
// Local Account
export const account = privateKeyToAccount(...)

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})
```
:::

## Return Value

`bigint`

The gas estimate.

## Parameters

### address

* **Type:** [`Address`](/docs/glossary/types#address)

The contract address.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2', // [!code focus]
  abi: wagmiAbi,
  functionName: 'mint',
  account,
})
```

### abi

* **Type:** [`Abi`](/docs/glossary/types#abi)

The contract's ABI.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi, // [!code focus]
  functionName: 'mint',
  account,
})
```

### functionName

* **Type:** `string`

A function to extract from the ABI.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint', // [!code focus]
  account,
})
```

### account

* **Type:** `Account | Address`

The Account to estimate gas from.

Accepts a [JSON-RPC Account](/docs/clients/wallet#json-rpc-accounts) or [Local Account (Private Key, etc)](/docs/clients/wallet#local-accounts-private-key-mnemonic-etc).

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  account: '0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266' // [!code focus]
})
```

### accessList (optional)

* **Type:** [`AccessList`](/docs/glossary/types#accesslist)

The access list.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  accessList: [{ // [!code focus:4]
    address: '0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266',
    storageKeys: ['0x1'],
  }],
  account,
})
```

### args (optional)

* **Type:** Inferred from ABI.

Arguments to pass to function call.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0x1dfe7ca09e99d10835bf73044a23b73fc20623df',
  abi: wagmiAbi,
  functionName: 'balanceOf',
  args: ['0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC'], // [!code focus]
  account,
})
```

### dataSuffix (optional)

* **Type:** `Hex`

Data to append to the end of the calldata. Useful for adding a ["domain" tag](https://opensea.notion.site/opensea/Seaport-Order-Attributions-ec2d69bf455041a5baa490941aad307f).

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  dataSuffix: '0xdeadbeef' // [!code focus]
})
```

### gasPrice (optional)

* **Type:** `bigint`

The price (in wei) to pay per gas. Only applies to [Legacy Transactions](/docs/glossary/terms#legacy-transaction).

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  account,
  gasPrice: parseGwei('20'), // [!code focus]
})
```

### maxFeePerGas (optional)

* **Type:** `bigint`

Total fee per gas (in wei), inclusive of `maxPriorityFeePerGas`. Only applies to [EIP-1559 Transactions](/docs/glossary/terms#eip-1559-transaction)

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  account,
  maxFeePerGas: parseGwei('20'),  // [!code focus]
})
```

### maxPriorityFeePerGas (optional)

* **Type:** `bigint`

Max priority fee per gas (in wei). Only applies to [EIP-1559 Transactions](/docs/glossary/terms#eip-1559-transaction)

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  account,
  maxFeePerGas: parseGwei('20'),
  maxPriorityFeePerGas: parseGwei('2'), // [!code focus]
})
```

### nonce (optional)

* **Type:** `number`

Unique number identifying this transaction.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  account,
  nonce: 69 // [!code focus]
})
```

### value (optional)

* **Type:** `number`

Value in wei sent with this transaction.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  args: [69420],
  account,
  value: parseEther('1') // [!code focus]
})
```

### blockNumber (optional)

* **Type:** `number`

The block number to perform the read against.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  account,
  blockNumber: 15121123n, // [!code focus]
})
```

### blockTag (optional)

* **Type:** `'latest' | 'earliest' | 'pending' | 'safe' | 'finalized'`
* **Default:** `'latest'`

The block tag to perform the read against.

```ts
const gas = await publicClient.estimateContractGas({
  address: '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2',
  abi: wagmiAbi,
  functionName: 'mint',
  account,
  blockTag: 'safe', // [!code focus]
})
```