estimateGas

The estimateGas function calculates the amount of gas required to execute a transaction without actually sending it to the blockchain, helping optimize transaction costs and prevent out-of-gas failures.

Gas estimation helps you set appropriate gas limits and fees before broadcasting transactions. It’s especially useful for complex transactions with unknown gas requirements.

Function Signature

function estimateGas(txRequest: TxRequest): Promise<number>

txRequest · TxRequest · required

Transaction request configuration including messages and optional parameters. The gas field is ignored for estimation.

Returns · Promise<number>

Promise that resolves to the estimated gas units required for the transaction.

Basic Usage

import { useInterwovenKit } from "@initia/interwovenkit-react"
import type { TxRequest, EncodeObject } from "@initia/interwovenkit-react"

function GasEstimationExample() {
  const { estimateGas, requestTxBlock, address } = useInterwovenKit()
  const [gasEstimate, setGasEstimate] = useState<number | null>(null)
  const [isEstimating, setIsEstimating] = useState(false)

  const estimateTransactionGas = async () => {
    setIsEstimating(true)

    const message: EncodeObject = {
      typeUrl: "/cosmos.bank.v1beta1.MsgSend",
      value: {
        fromAddress: address,
        toAddress: "init1recipient...",
        amount: [{ denom: "uinit", amount: "1000000" }]
      }
    }

    const txRequest: TxRequest = {
      messages: [message],
      memo: "Gas estimation test"
    }

    try {
      const estimate = await estimateGas(txRequest)
      setGasEstimate(estimate)
      console.log("Estimated gas:", estimate)
    } catch (error) {
      console.error("Gas estimation failed:", error)
    } finally {
      setIsEstimating(false)
    }
  }

  const sendWithEstimatedGas = async () => {
    if (!gasEstimate) return

    const txRequest: TxRequest = {
      messages: [/* same messages */],
      gas: Math.floor(gasEstimate * 1.2), // 20% buffer
      memo: "Transaction with estimated gas"
    }

    await requestTxBlock(txRequest)
  }

  return (
    <div className="gas-estimation-example">
      <button onClick={estimateTransactionGas} disabled={isEstimating}>
        {isEstimating ? "Estimating..." : "Estimate Gas"}
      </button>
      
      {gasEstimate && (
        <div className="gas-info">
          <p>Estimated Gas: {gasEstimate.toLocaleString()} units</p>
          <p>With 20% buffer: {Math.floor(gasEstimate * 1.2).toLocaleString()} units</p>
          <button onClick={sendWithEstimatedGas}>
            Send with Estimated Gas
          </button>
        </div>
      )}
    </div>
  )
}

Gas Estimation for Multiple Messages

async function estimateBatchGas(estimateGas, messages) {
  try {
    const gasEstimate = await estimateGas({ messages })
    console.log("Estimated gas for batch:", gasEstimate)
    return gasEstimate
  } catch (error) {
    console.error("Gas estimation failed:", error)
    throw error
  }
}

Using Gas Estimates

async function sendWithEstimatedGas(estimateGas, requestTxBlock, messages) {
  try {
    const baseEstimate = await estimateGas({ messages })
    const gasLimit = Math.floor(baseEstimate * 1.3) // 30% buffer
    
    const response = await requestTxBlock({
      messages,
      gas: gasLimit
    })

    console.log("Transaction successful")
    return response
  } catch (error) {
    console.error("Transaction failed:", error)
    throw error
  }
}

Error Handling

Handle gas estimation failures gracefully:

async function estimateGasWithFallback(estimateGas, messages) {
  try {
    return await estimateGas({ messages })
  } catch (error) {
    console.warn("Gas estimation failed:", error.message)
    // Fallback to conservative estimate
    return messages.length * 50000
  }
}

Fee Calculation with Gas Estimates

Combine gas estimation with fee calculation for precise transaction cost control:

import { calculateFee, GasPrice } from "@cosmjs/stargate"
import { useInterwovenKit } from "@initia/interwovenkit-react"

function PreciseCostTransaction() {
  const { estimateGas, requestTxBlock, address } = useInterwovenKit()

  const sendWithPreciseFee = async () => {
    const messages: EncodeObject[] = [{
      typeUrl: "/cosmos.bank.v1beta1.MsgSend",
      value: {
        fromAddress: address,
        toAddress: "init1recipient...",
        amount: [{ denom: "uinit", amount: "1000000" }]
      }
    }]

    try {
      // Estimate gas requirement
      const gasEstimate = await estimateGas({ messages })
      
      // Apply safety margin
      const gasLimit = Math.ceil(gasEstimate * 1.5)
      
      // Calculate precise fee
      const fee = calculateFee(gasLimit, GasPrice.fromString("0.015uinit"))

      console.log("Gas estimate:", gasEstimate)
      console.log("Gas limit with buffer:", gasLimit)
      console.log("Calculated fee:", fee)

      const response = await requestTxBlock({
        messages,
        fee, // Use calculated fee
        memo: "Transaction with precise cost calculation"
      })

      if (response.code === 0) {
        console.log("Precise cost transaction successful!")
        console.log("Actual gas used:", response.gasUsed)
        console.log("Gas efficiency:", `${(Number(response.gasUsed) / gasLimit * 100).toFixed(1)}%`)
      }
    } catch (error) {
      console.error("Precise cost transaction failed:", error)
    }
  }

  return (
    <button onClick={sendWithPreciseFee}>
      Send with Precise Cost
    </button>
  )
}

Cost Comparison Analysis

function GasCostAnalysis() {
  const { estimateGas } = useInterwovenKit()

  const analyzeCosts = async (messages: EncodeObject[]) => {
    const gasEstimate = await estimateGas({ messages })
    
    // Compare costs with different gas prices
    const gasPrices = ["0.010uinit", "0.015uinit", "0.025uinit"]
    const adjustments = [1.2, 1.5, 1.8]

    console.log("Gas Cost Analysis:")
    console.log("Base gas estimate:", gasEstimate)
    
    gasPrices.forEach(priceStr => {
      adjustments.forEach(adj => {
        const gasLimit = Math.ceil(gasEstimate * adj)
        const fee = calculateFee(gasLimit, GasPrice.fromString(priceStr))
        console.log(`${priceStr} @ ${adj}x: ${fee.amount[0].amount} units`)
      })
    })
  }

  return analyzeCosts
}

Use estimateGas with calculateFee for optimal transaction cost control. For comprehensive fee calculation examples and patterns, see the Fee Calculation Utilities guide.

The estimateGas function calculates the gas required for transaction execution before broadcasting, allowing for accurate cost estimation and gas limit setting.