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eth_estimateGas

Generates and returns an estimate of how much gas is necessary to allow the transaction to complete. The transaction will not be added to the blockchain.

When to Use This Method​

eth_estimateGas is crucial for:

  • Transaction Preparation - Calculate gas limits before sending
  • Cost Estimation - Preview transaction fees for users
  • Gas Optimization - Find optimal gas usage for complex operations
  • Error Prevention - Detect failures before broadcasting

Parameters​

  1. Transaction Object

    • from - (optional) Address sending the transaction
    • to - Address of receiver or contract
    • gas - (optional) Gas limit for estimation
    • gasPrice - (optional) Gas price in wei
    • value - (optional) Value to send in wei
    • data - (optional) Hash of method signature and encoded parameters

  2. Block Parameter - QUANTITY|TAG (optional)

    • "latest" - Most recent block (default)
    • "pending" - Pending state
    • Block number in hex
{
  "jsonrpc": "2.0",
  "method": "eth_estimateGas",
  "params": [
    {
      "from": "0xb60e8dd61c5d32be8058bb8eb970870f07233155",
      "to": "0xd46e8dd67c5d32be8058bb8eb970870f07244567",
      "value": "0x9184e72a",
      "data": "0xd46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675"
    }
  ],
  "id": 1
}

Returns​

QUANTITY - The estimated gas amount in hexadecimal.

Implementation Examples​

import { JsonRpcProvider, Contract, parseEther, parseUnits } from 'ethers';

const provider = new JsonRpcProvider('https://api-arbitrum-mainnet-archive.n.dwellir.com/YOUR_API_KEY');

// Gas estimation utility
class GasEstimator {
  constructor(provider) {
    this.provider = provider;
    this.cache = new Map();
  }

  async estimateETHTransfer(from, to, value) {
    try {
      const gasEstimate = await this.provider.estimateGas({
        from: from,
        to: to,
        value: parseEther(value)
      });

      // Add 10% buffer for safety
      const gasWithBuffer = gasEstimate * 110n / 100n;

      // Get current gas prices
      const feeData = await this.provider.getFeeData();
      
      // Calculate costs
      const estimatedCost = gasWithBuffer * feeData.gasPrice;
      const estimatedCostEIP1559 = gasWithBuffer * feeData.maxFeePerGas;

      return {
        gasLimit: gasWithBuffer.toString(),
        gasPrice: feeData.gasPrice.toString(),
        maxFeePerGas: feeData.maxFeePerGas.toString(),
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas.toString(),
        estimatedCostWei: estimatedCost.toString(),
        estimatedCostETH: ethers.formatEther(estimatedCost),
        estimatedCostEIP1559Wei: estimatedCostEIP1559.toString(),
        estimatedCostEIP1559ETH: ethers.formatEther(estimatedCostEIP1559)
      };
    } catch (error) {
      throw new Error(`Gas estimation failed: ${error.message}`);
    }
  }

  async estimateContractCall(contractAddress, abi, method, params, from) {
    const contract = new Contract(contractAddress, abi, this.provider);
    
    try {
      // Build transaction
      const tx = await contract[method].populateTransaction(...params);
      tx.from = from;

      // Estimate gas
      const gasEstimate = await this.provider.estimateGas(tx);
      
      // Get L1 fee estimate for Arbitrum L1
      const l1FeeEstimate = await this.estimateL1Fee(tx);
      
      // Calculate total with buffer
      const gasWithBuffer = gasEstimate * 115n / 100n; // 15% buffer for contracts
      
      const feeData = await this.provider.getFeeData();
      const l2Cost = gasWithBuffer * feeData.maxFeePerGas;
      const totalCost = l2Cost + l1FeeEstimate;

      return {
        gasLimit: gasWithBuffer.toString(),
        l2GasEstimate: gasEstimate.toString(),
        l1FeeEstimate: l1FeeEstimate.toString(),
        maxFeePerGas: feeData.maxFeePerGas.toString(),
        l2CostWei: l2Cost.toString(),
        l2CostETH: ethers.formatEther(l2Cost),
        totalCostWei: totalCost.toString(),
        totalCostETH: ethers.formatEther(totalCost),
        method: method,
        contract: contractAddress
      };
    } catch (error) {
      // Parse revert reason if available
      if (error.data) {
        const reason = this.parseRevertReason(error.data);
        throw new Error(`Estimation failed: ${reason}`);
      }
      throw error;
    }
  }

  async estimateL1Fee(transaction) {
    // Arbitrum L1 specific - estimate L1 data posting fee
    try {
      // This would call a Base-specific method if available
      // For now, estimate based on transaction size
      const txData = JSON.stringify(transaction);
      const dataSize = new Blob([txData]).size;
      
      // Rough estimate: ~16 gas per byte on L1
      const l1GasEstimate = BigInt(dataSize * 16);
      const l1GasPrice = await this.provider.getGasPrice(); // L1 gas price
      
      return l1GasEstimate * l1GasPrice / 10n; // Adjusted for L2 economics
    } catch {
      return 0n;
    }
  }

  parseRevertReason(data) {
    if (typeof data === 'string' && data.startsWith('0x08c379a0')) {
      // Standard revert string
      const reason = ethers.AbiCoder.defaultAbiCoder().decode(
        ['string'],
        '0x' + data.slice(10)
      )[0];
      return reason;
    }
    return 'Unknown error';
  }

  async batchEstimate(transactions) {
    const estimates = [];
    
    for (const tx of transactions) {
      try {
        const gasEstimate = await this.provider.estimateGas(tx);
        const feeData = await this.provider.getFeeData();
        
        estimates.push({
          transaction: tx,
          gasLimit: gasEstimate.toString(),
          estimatedCost: (gasEstimate * feeData.maxFeePerGas).toString(),
          success: true
        });
      } catch (error) {
        estimates.push({
          transaction: tx,
          error: error.message,
          success: false
        });
      }
    }
    
    return estimates;
  }

  async compareGasStrategies(transaction) {
    const gasEstimate = await this.provider.estimateGas(transaction);
    const feeData = await this.provider.getFeeData();
    const block = await this.provider.getBlock('latest');
    
    // Different gas strategies
    const strategies = {
      conservative: {
        gasLimit: gasEstimate * 150n / 100n, // 50% buffer
        maxFeePerGas: feeData.maxFeePerGas * 120n / 100n,
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas * 120n / 100n
      },
      standard: {
        gasLimit: gasEstimate * 110n / 100n, // 10% buffer
        maxFeePerGas: feeData.maxFeePerGas,
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas
      },
      aggressive: {
        gasLimit: gasEstimate * 105n / 100n, // 5% buffer
        maxFeePerGas: block.baseFeePerGas * 2n + feeData.maxPriorityFeePerGas / 2n,
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas / 2n
      }
    };
    
    const results = {};
    for (const [name, strategy] of Object.entries(strategies)) {
      const maxCost = strategy.gasLimit * strategy.maxFeePerGas;
      const likelyCost = strategy.gasLimit * 
        (block.baseFeePerGas + strategy.maxPriorityFeePerGas);
      
      results[name] = {
        ...strategy,
        maxCostWei: maxCost.toString(),
        maxCostETH: ethers.formatEther(maxCost),
        likelyCostWei: likelyCost.toString(),
        likelyCostETH: ethers.formatEther(likelyCost)
      };
    }
    
    return results;
  }
}

// Usage example
const estimator = new GasEstimator(provider);

// Estimate simple transfer
const transferEstimate = await estimator.estimateETHTransfer(
  '0xYourAddress',
  '0xRecipientAddress',
  '0.1'
);
console.log('Transfer cost:', transferEstimate.estimatedCostETH, 'ETH');

// Estimate contract interaction
const contractEstimate = await estimator.estimateContractCall(
  '0xContractAddress',
  ['function transfer(address to, uint256 amount)'],
  'transfer',
  ['0xRecipient', parseUnits('100', 18)],
  '0xYourAddress'
);
console.log('Contract call cost:', contractEstimate.totalCostETH, 'ETH');

Common Use Cases​

1. Pre-Transaction Validation​

// Validate transaction before sending
async function validateTransaction(from, to, value, data) {
  try {
    const gasEstimate = await provider.estimateGas({
      from: from,
      to: to,
      value: value,
      data: data
    });
    
    // Check if account has enough balance
    const balance = await provider.getBalance(from);
    const feeData = await provider.getFeeData();
    const maxCost = value + (gasEstimate * feeData.maxFeePerGas);
    
    if (balance < maxCost) {
      return {
        valid: false,
        reason: 'Insufficient balance',
        required: ethers.formatEther(maxCost),
        available: ethers.formatEther(balance)
      };
    }
    
    return {
      valid: true,
      gasLimit: gasEstimate.toString(),
      estimatedFee: ethers.formatEther(gasEstimate * feeData.gasPrice)
    };
  } catch (error) {
    return {
      valid: false,
      reason: error.message
    };
  }
}

2. Dynamic Gas Pricing UI​

// Real-time gas price updates for UI
class GasPriceMonitor {
  constructor(provider) {
    this.provider = provider;
    this.listeners = [];
  }
  
  async getCurrentPrices() {
    const [feeData, block] = await Promise.all([
      this.provider.getFeeData(),
      this.provider.getBlock('latest')
    ]);
    
    return {
      slow: {
        maxFeePerGas: feeData.maxFeePerGas * 90n / 100n,
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas * 80n / 100n,
        estimatedTime: '2-5 minutes'
      },
      standard: {
        maxFeePerGas: feeData.maxFeePerGas,
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas,
        estimatedTime: '15-30 seconds'
      },
      fast: {
        maxFeePerGas: feeData.maxFeePerGas * 120n / 100n,
        maxPriorityFeePerGas: feeData.maxPriorityFeePerGas * 150n / 100n,
        estimatedTime: '5-15 seconds'
      },
      baseFee: block.baseFeePerGas
    };
  }
  
  async estimateForTransaction(tx, speed = 'standard') {
    const prices = await this.getCurrentPrices();
    const gasEstimate = await this.provider.estimateGas(tx);
    const settings = prices[speed];
    
    return {
      gasLimit: gasEstimate,
      ...settings,
      estimatedCost: ethers.formatEther(gasEstimate * settings.maxFeePerGas),
      maxCost: ethers.formatEther(gasEstimate * settings.maxFeePerGas)
    };
  }
}

3. Batch Operation Optimization​

// Optimize gas for batch operations
async function optimizeBatchTransactions(transactions) {
  const estimates = [];
  let totalGas = 0n;
  
  // Estimate individually
  for (const tx of transactions) {
    const estimate = await provider.estimateGas(tx);
    estimates.push(estimate);
    totalGas += estimate;
  }
  
  // Check if multicall is more efficient
  const multicallEstimate = await estimateMulticall(transactions);
  
  if (multicallEstimate < totalGas * 90n / 100n) {
    return {
      method: 'multicall',
      gasLimit: multicallEstimate,
      savings: ethers.formatUnits(totalGas - multicallEstimate, 'gwei')
    };
  }
  
  return {
    method: 'individual',
    gasLimits: estimates,
    totalGas: totalGas
  };
}

Error Handling​

Error TypeDescriptionSolution
Execution revertedTransaction would failCheck contract requirements
Gas required exceeds limitBlock gas limit exceededSplit into smaller transactions
Insufficient fundsNot enough ETH for gasAdd funds or reduce gas price
async function safeEstimate(transaction) {
  try {
    const estimate = await provider.estimateGas(transaction);
    return { success: true, gasLimit: estimate };
  } catch (error) {
    // Parse error for useful information
    const errorString = error.toString();
    
    if (errorString.includes('execution reverted')) {
      // Try to get revert reason
      try {
        await provider.call(transaction);
      } catch (callError) {
        return {
          success: false,
          error: 'Transaction would revert',
          reason: callError.reason || 'Unknown reason'
        };
      }
    }
    
    if (errorString.includes('gas required exceeds')) {
      return {
        success: false,
        error: 'Gas limit exceeded',
        suggestion: 'Try splitting into smaller operations'
      };
    }
    
    return {
      success: false,
      error: error.message
    };
  }
}

Need help? Contact our support team or check the Arbitrum documentation.