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# Estimate Priority Fee \[fee.estimateMaxPriorityFeePerGas]

Returns an estimate for the max priority fee per gas (in wei) for a transaction to be likely included in the next block.

## Usage

This example returns an estimate for the max priority fee per gas (in wei) for a transaction to be likely included in the next block.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const maxPriorityFeePerGas = await client.fee.estimateMaxPriorityFeePerGas()
// @log: 1500000000n
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
import { Client, http, publicActions } from 'viem'
import { mainnet } from 'viem/chains'

export const client = Client.create({
  chain: mainnet,
  transport: http(),
}).extend(publicActions())
```
:::

### Standalone Action

Call `Actions.fee.estimateMaxPriorityFeePerGas` directly by passing the Client as the first argument.

:::code-group
```ts twoslash [example.ts]
import { Actions } from 'viem'
import { client } from './viem.config'

const maxPriorityFeePerGas = await Actions.fee.estimateMaxPriorityFeePerGas(client)
// @log: 1500000000n
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
import { Client, http } from 'viem'
import { mainnet } from 'viem/chains'

export const client = Client.create({
  chain: mainnet,
  transport: http(),
})
```
:::

The estimate is derived in the following order:

1. The Client chain's [`fees.maxPriorityFeePerGas`](/docs/chains), if set.
2. The `eth_maxPriorityFeePerGas` RPC method, if the provider supports it.
3. A fallback of `gasPrice - baseFeePerGas` (returning `0n` if negative).

## Return Value

`bigint`

An estimate (in wei) for the max priority fee per gas.

## Parameters

### chain

* **Type:** `Chain`
* **Default:** the Client's `chain`

Chain to use for fee derivation. Override the Client's chain to apply a different chain's [`fees`](/docs/chains) configuration.

```ts twoslash
import { Actions, Client, http } from 'viem'
import { mainnet } from 'viem/chains'

const client = Client.create({ transport: http() })
// ---cut---
const maxPriorityFeePerGas = await Actions.fee.estimateMaxPriorityFeePerGas(client, {
  chain: mainnet, // [!code focus]
})
```

## Errors

| Error | Description |
| --- | --- |
| `Actions.fee.Errors.Eip1559FeesNotSupportedError` | The chain does not support EIP-1559 fees (no `baseFeePerGas` on the latest block). |