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# Estimate Gas and Fees

## Overview

Gas estimates predict execution units, while fee estimates price each unit. Use
[`transaction.estimateGas`](/docs/actions/public/transaction/estimateGas) for a specific request and
[`fee.estimateFeesPerGas`](/docs/actions/public/fee/estimateFeesPerGas) for EIP-1559 or legacy fee
parameters.

## Recipes

These recipes assume you have [set up a Client](/docs) with [`publicActions`](/docs/actions/public).

### Estimate Transaction Gas

Include the sender when execution depends on `msg.sender` or the sender's balance.

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

const gas = await client.transaction.estimateGas({ // [!code focus]
  account: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e', // [!code focus]
  to: '0x70997970c51812dc3a010c7d01b50e0d17dc79c8', // [!code focus]
  value: Value.fromEther('1'), // [!code focus]
}) // [!code focus]
// @log: 21000n
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/public.config.ts:setup]
```
:::

### Estimate EIP-1559 Fees

The result contains the maximum total fee and priority fee per gas.

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

const fees = await client.fee.estimateFeesPerGas() // [!code focus]
// @log: { maxFeePerGas: 15040000000n, maxPriorityFeePerGas: 1000000000n }
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/public.config.ts:setup]
```
:::

### Inspect Fee History

Use [`fee.getHistory`](/docs/actions/public/fee/getHistory) to build a custom fee strategy from
recent base fees, gas usage, and priority fee rewards.

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

const history = await client.fee.getHistory({ // [!code focus]
  blockCount: 4, // [!code focus]
  rewardPercentiles: [25, 50, 75], // [!code focus]
}) // [!code focus]
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/public.config.ts:setup]
```
:::

### Read Priority and Blob Fees

Use
[`fee.estimateMaxPriorityFeePerGas`](/docs/actions/public/fee/estimateMaxPriorityFeePerGas) for the
likely inclusion tip and [`fee.getBlobBaseFee`](/docs/actions/public/fee/getBlobBaseFee) for the
current blob-gas base fee.

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

const [maxPriorityFeePerGas, blobBaseFee] = await Promise.all([
  client.fee.estimateMaxPriorityFeePerGas(), // [!code focus]
  client.fee.getBlobBaseFee(), // [!code focus]
])
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/docs/public.config.ts:setup]
```
:::

## Best Practices

### Estimate the Final Request

Estimate with the same sender, recipient, value, calldata, and authorization list that will be
submitted. Small request changes can produce materially different gas usage.

### Use Chain Fee Configuration

Prefer Chain-level fee hooks for network-specific behavior. Keep per-request overrides for user
choices or exceptional transactions.

## See More

<Cards>
  <Card icon="lucide:send" title="Send Transactions" description="Apply fee estimates to a transaction request." to="/docs/guides/transactions/send" />

  <Card icon="lucide:settings" title="Chain Fees" description="Configure network-specific fee estimation behavior." to="/docs/chains/fees" />
</Cards>