Fees
You can modify how fees are derived by using the fees property on the Chain.
Usage
tsx
import { defineChain } from 'viem'
export const example = defineChain({
/* ... */
fees: {
baseFeeMultiplier: 1.2,
defaultPriorityFee: parseGwei('0.01'),
}
})import { defineChain } from 'viem'
export const example = defineChain({
/* ... */
fees: {
baseFeeMultiplier: 1.2,
defaultPriorityFee: parseGwei('0.01'),
}
})API
fees.baseFeeMultiplier
- Type:
number - Default:
1.2
The fee multiplier to use to account for fee fluctuations. Used in the estimateFeesPerGas Action against the latest block's base fee per gas to derive a final maxFeePerGas (EIP-1193), or gas price to derive a final gasPrice (Legacy).
Parameters
block: The latest block.client: The Client instance.request: The transaction request (if exists).
ts
import { defineChain } from 'viem'
const example = defineChain({
/* ... */
fees: {
baseFeeMultiplier: 1.2,
// or
async baseFeeMultiplier({ block, request }) {
// some async work
return // ...
},
},
})import { defineChain } from 'viem'
const example = defineChain({
/* ... */
fees: {
baseFeeMultiplier: 1.2,
// or
async baseFeeMultiplier({ block, request }) {
// some async work
return // ...
},
},
})fees.defaultPriorityFee
- Type:
number | ((args: FeesFnParameters) => Promise<bigint> | bigint)
The default maxPriorityFeePerGas to use when a priority fee is not defined upon sending a transaction.
Also overrides the return value in the estimateMaxPriorityFeePerGas Action and maxPriorityFeePerGas value in estimateFeesPerGas.
Parameters
block: The latest block.client: The Client instance.request: The transaction request (if exists).
ts
import { defineChain } from 'viem'
const example = defineChain({
/* ... */
fees: {
defaultPriorityFee: parseGwei('0.01'),
// or
async defaultPriorityFee({ block, request }) {
// some async work
return // ...
},
},
})import { defineChain } from 'viem'
const example = defineChain({
/* ... */
fees: {
defaultPriorityFee: parseGwei('0.01'),
// or
async defaultPriorityFee({ block, request }) {
// some async work
return // ...
},
},
})fees.estimateFeesPerGas
- Type:
(args: FeesFnParameters) => Promise<EstimateFeesPerGasResponse>
Allows customization of fee per gas values (ie. maxFeePerGas, maxPriorityFeePerGas, gasPrice).
Also overrides the return value in estimateFeesPerGas.
Parameters
block: The latest block.client: The Client instance.multiply: A function to apply thebaseFeeMultiplierto the provided value.request: The transaction request (if exists).type: The transaction type (ie.legacyoreip1559).
ts
import { defineChain } from 'viem'
const example = defineChain({
/* ... */
fees: {
async estimateFeesPerGas({ client, multiply, type }) {
const gasPrice = // ...
const baseFeePerGas = // ...
const maxPriorityFeePerGas = // ...
if (type === 'legacy') return { gasPrice: multiply(gasPrice) }
return {
maxFeePerGas: multiply(baseFeePerGas) + maxPriorityFeePerGas,
maxPriorityFeePerGas
},
},
},
})import { defineChain } from 'viem'
const example = defineChain({
/* ... */
fees: {
async estimateFeesPerGas({ client, multiply, type }) {
const gasPrice = // ...
const baseFeePerGas = // ...
const maxPriorityFeePerGas = // ...
if (type === 'legacy') return { gasPrice: multiply(gasPrice) }
return {
maxFeePerGas: multiply(baseFeePerGas) + maxPriorityFeePerGas,
maxPriorityFeePerGas
},
},
},
})