InterwovenKit integrates with CosmJS utilities for calculating transaction fees programmatically, giving you precise control over fee amounts and gas prices.
These utilities are imported from @cosmjs/stargate and are commonly used with InterwovenKit transaction methods for custom fee handling.
calculateFee Function
Calculates the total fee for a transaction based on gas limit and gas price.
Function Signature
function calculateFee(gasLimit: number, gasPrice: GasPrice): StdFee
The gas limit for the transaction (usually obtained from estimateGas).
Gas price object created with GasPrice.fromString().
Complete fee structure with amount and gas limit.
Basic Usage
import { calculateFee, GasPrice } from "@cosmjs/stargate"
import { useInterwovenKit } from "@initia/interwovenkit-react"
import type { TxRequest, EncodeObject } from "@initia/interwovenkit-react"
function PreciseFeeTransaction() {
const { requestTxBlock, estimateGas, address } = useInterwovenKit()
const sendWithCalculatedFee = async () => {
const messages: EncodeObject[] = [{
typeUrl: "/cosmos.bank.v1beta1.MsgSend",
value: {
fromAddress: address,
toAddress: "init1recipient...",
amount: [{ denom: "uinit", amount: "1000000" }]
}
}]
try {
// Estimate gas needed for the transaction
const gasLimit = await estimateGas({ messages })
// Calculate fee with specific gas price
const fee = calculateFee(gasLimit, GasPrice.fromString("0.015uinit"))
const txRequest: TxRequest = {
messages,
fee, // Use calculated fee
memo: "Transaction with precise fee calculation"
}
const response = await requestTxBlock(txRequest)
if (response.code === 0) {
console.log("Precise fee transaction successful!")
console.log("Actual fee paid:", response.gasUsed)
}
} catch (error) {
console.error("Fee calculation error:", error)
}
}
return (
<button onClick={sendWithCalculatedFee}>
Send with Calculated Fee
</button>
)
}
GasPrice Class
Represents gas prices for different token denominations.
GasPrice.fromString()
Creates a GasPrice instance from a string representation.
Function Signature
static fromString(gasPrice: string): GasPrice
Gas price as a string with amount and denomination (e.g., “0.015uinit”, “0.025uusdc”).
GasPrice instance for use with calculateFee.
Usage Examples
import { GasPrice, calculateFee } from "@cosmjs/stargate"
// Create gas prices for different denominations
const initGasPrice = GasPrice.fromString("0.015uinit")
const usdcGasPrice = GasPrice.fromString("0.025uusdc")
// Calculate fees with different gas prices
const gasLimit = 200000
const initFee = calculateFee(gasLimit, initGasPrice)
const usdcFee = calculateFee(gasLimit, usdcGasPrice)
console.log("INIT fee:", initFee)
// { amount: [{ denom: "uinit", amount: "3000" }], gas: "200000" }
console.log("USDC fee:", usdcFee)
// { amount: [{ denom: "uusdc", amount: "5000" }], gas: "200000" }
Advanced Fee Calculations
Dynamic Gas Price Selection
import { calculateFee, GasPrice } from "@cosmjs/stargate"
import { useInterwovenKit } from "@initia/interwovenkit-react"
function DynamicFeeTransaction() {
const { requestTxBlock, estimateGas, address } = useInterwovenKit()
const getOptimalFee = async (messages: EncodeObject[], priority: 'low' | 'standard' | 'high') => {
const gasLimit = await estimateGas({ messages })
// Define gas prices by priority
const gasPrices = {
low: "0.010uinit",
standard: "0.015uinit",
high: "0.025uinit"
}
return calculateFee(gasLimit, GasPrice.fromString(gasPrices[priority]))
}
const sendWithPriority = async (priority: 'low' | 'standard' | 'high') => {
const messages: EncodeObject[] = [{
typeUrl: "/cosmos.bank.v1beta1.MsgSend",
value: {
fromAddress: address,
toAddress: "init1recipient...",
amount: [{ denom: "uinit", amount: "1000000" }]
}
}]
try {
const fee = await getOptimalFee(messages, priority)
const response = await requestTxBlock({
messages,
fee,
memo: `Transaction with ${priority} priority fee`
})
console.log(`${priority} priority transaction sent:`, response.transactionHash)
} catch (error) {
console.error(`${priority} priority transaction failed:`, error)
}
}
return (
<div className="priority-controls">
<button onClick={() => sendWithPriority('low')}>
Send (Low Fee)
</button>
<button onClick={() => sendWithPriority('standard')}>
Send (Standard Fee)
</button>
<button onClick={() => sendWithPriority('high')}>
Send (High Fee)
</button>
</div>
)
}
Gas Adjustment with Fee Calculation
import { calculateFee, GasPrice } from "@cosmjs/stargate"
import { useInterwovenKit } from "@initia/interwovenkit-react"
function AdjustedFeeTransaction() {
const { requestTxBlock, estimateGas } = useInterwovenKit()
const sendWithGasAdjustment = async (messages: EncodeObject[], adjustment = 1.5) => {
try {
const estimatedGas = await estimateGas({ messages })
// Apply gas adjustment for safety margin
const adjustedGasLimit = Math.ceil(estimatedGas * adjustment)
// Calculate fee with adjusted gas limit
const fee = calculateFee(adjustedGasLimit, GasPrice.fromString("0.015uinit"))
const response = await requestTxBlock({
messages,
fee,
memo: `Transaction with ${adjustment}x gas adjustment`
})
console.log("Adjusted fee transaction successful!")
console.log("Gas estimated:", estimatedGas)
console.log("Gas used:", response.gasUsed)
console.log("Gas limit set:", adjustedGasLimit)
} catch (error) {
console.error("Adjusted fee transaction failed:", error)
}
}
return (
<button onClick={() => sendWithGasAdjustment([/* messages */], 1.8)}>
Send with 1.8x Gas Adjustment
</button>
)
}
Multi-Denomination Fee Support
import { calculateFee, GasPrice } from "@cosmjs/stargate"
function MultiDenomFeeComparison() {
const compareFeeCosts = async (gasLimit: number) => {
// Calculate fees in different denominations
const fees = [
{ denom: "uinit", fee: calculateFee(gasLimit, GasPrice.fromString("0.015uinit")) },
{ denom: "uusdc", fee: calculateFee(gasLimit, GasPrice.fromString("0.025uusdc")) },
{ denom: "uatom", fee: calculateFee(gasLimit, GasPrice.fromString("0.020uatom")) }
]
fees.forEach(({ denom, fee }) => {
console.log(`${denom} fee:`, fee.amount[0])
})
return fees
}
return compareFeeCosts
}
Integration with Transaction Methods
With requestTxBlock
const fee = calculateFee(gasLimit, GasPrice.fromString("0.015uinit"))
const response = await requestTxBlock({
messages,
fee, // Calculated fee
memo: "Transaction with calculated fee"
})
With requestTxSync
const fee = calculateFee(gasLimit, GasPrice.fromString("0.015uinit"))
const txHash = await requestTxSync({
messages,
fee, // Calculated fee
memo: "Async transaction with calculated fee"
})
With estimateGas
// Get gas estimate first
const gasLimit = await estimateGas({ messages })
// Then calculate precise fee
const fee = calculateFee(gasLimit, GasPrice.fromString("0.015uinit"))
Always use estimateGas to get accurate gas limits before calculating fees. Apply gas adjustments (usually 1.4-1.8x) to provide safety margins for complex transactions.
Gas prices should match the network’s accepted denominations. Check the chain configuration or use the gas prices returned by useGasPrices hook for dynamic pricing.
Common Patterns
Fee Calculation with Error Handling
async function safeCalculateFee(messages: EncodeObject[], gasPrice: string) {
try {
const gasLimit = await estimateGas({ messages })
return calculateFee(gasLimit, GasPrice.fromString(gasPrice))
} catch (error) {
console.error("Fee calculation failed:", error)
// Fallback to default fee
return {
amount: [{ denom: "uinit", amount: "5000" }],
gas: "200000"
}
}
}
Optimal Fee Selection
async function selectOptimalFee(messages: EncodeObject[], balances: Coin[]) {
const gasLimit = await estimateGas({ messages })
const availableFees = [
calculateFee(gasLimit, GasPrice.fromString("0.015uinit")),
calculateFee(gasLimit, GasPrice.fromString("0.025uusdc"))
]
// Select fee based on available balance
for (const fee of availableFees) {
const feeDenom = fee.amount[0].denom
const balance = balances.find(b => b.denom === feeDenom)?.amount ?? "0"
if (BigInt(balance) >= BigInt(fee.amount[0].amount)) {
return fee
}
}
throw new Error("Insufficient balance for any fee option")
}
