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

cURL

# Estimate simple ETH transfer
curl -X POST https://api-ethereum-mainnet.n.dwellir.com/YOUR_API_KEY \
-H "Content-Type: application/json" \
-d '{
  "jsonrpc": "2.0",
  "method": "eth_estimateGas",
  "params": [{
    "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "to": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "value": "0x9184e72a"
  }, "latest"],
  "id": 1
}'

# Estimate contract interaction
curl -X POST https://api-ethereum-mainnet.n.dwellir.com/YOUR_API_KEY \
-H "Content-Type: application/json" \
-d '{
  "jsonrpc": "2.0",
  "method": "eth_estimateGas",
  "params": [{
    "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
    "to": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    "data": "0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000000000001"
  }, "latest"],
  "id": 1
}'

JavaScript

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

const provider = new JsonRpcProvider('${S.rpcBase}');

// 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 Ethereum Mainnet
      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) {
    // Ethereum Mainnet specific - estimate L1 data posting fee
    try {
      // This would call a Ethereum-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');

Python

from web3 import Web3
from eth_utils import to_wei, from_wei
import json
from typing import Dict, Any, List, Optional

w3 = Web3(Web3.HTTPProvider('${S.rpcBase}'))

class GasCalculator:
    """Calculate and optimize gas for Ethereum Mainnet transactions"""
    
    def __init__(self, w3_instance):
        self.w3 = w3_instance
    
    def estimate_transfer(
        self, 
        from_address: str, 
        to_address: str, 
        value_eth: float
    ) -> Dict[str, Any]:
        """Estimate gas for ETH transfer"""
        
        try:
            # Build transaction
            transaction = {
                'from': from_address,
                'to': to_address,
                'value': to_wei(value_eth, 'ether')
            }
            
            # Estimate gas
            gas_estimate = self.w3.eth.estimate_gas(transaction)
            
            # Add buffer
            gas_limit = int(gas_estimate * 1.1)  # 10% buffer
            
            # Get current gas prices
            gas_price = self.w3.eth.gas_price
            base_fee = self.w3.eth.get_block('latest')['baseFeePerGas']
            max_priority_fee = self.w3.eth.max_priority_fee
            
            # Calculate costs
            estimated_cost = gas_limit * gas_price
            max_cost = gas_limit * (base_fee * 2 + max_priority_fee)
            
            return {
                'gas_estimate': gas_estimate,
                'gas_limit': gas_limit,
                'gas_price_gwei': from_wei(gas_price, 'gwei'),
                'base_fee_gwei': from_wei(base_fee, 'gwei'),
                'priority_fee_gwei': from_wei(max_priority_fee, 'gwei'),
                'estimated_cost_eth': from_wei(estimated_cost, 'ether'),
                'max_cost_eth': from_wei(max_cost, 'ether')
            }
            
        except Exception as e:
            return {'error': str(e)}
    
    def estimate_contract_call(
        self,
        from_address: str,
        to_address: str,
        data: str,
        value: int = 0
    ) -> Dict[str, Any]:
        """Estimate gas for contract interaction"""
        
        transaction = {
            'from': from_address,
            'to': to_address,
            'data': data,
            'value': value
        }
        
        try:
            # Estimate gas
            gas_estimate = self.w3.eth.estimate_gas(transaction)
            
            # Estimate L1 fee component (Ethereum specific)
            l1_fee = self._estimate_l1_fee(transaction)
            
            # Calculate with buffer
            gas_limit = int(gas_estimate * 1.15)  # 15% buffer for contracts
            
            # Get fee data
            gas_price = self.w3.eth.gas_price
            
            # Calculate costs
            l2_cost = gas_limit * gas_price
            total_cost = l2_cost + l1_fee
            
            return {
                'success': True,
                'gas_estimate': gas_estimate,
                'gas_limit': gas_limit,
                'l1_fee_wei': l1_fee,
                'l2_cost_wei': l2_cost,
                'total_cost_wei': total_cost,
                'total_cost_eth': from_wei(total_cost, 'ether'),
                'breakdown': {
                    'l2_cost_eth': from_wei(l2_cost, 'ether'),
                    'l1_fee_eth': from_wei(l1_fee, 'ether')
                }
            }
            
        except Exception as e:
            # Try to extract revert reason
            error_msg = str(e)
            if 'execution reverted' in error_msg:
                return {
                    'success': False,
                    'error': 'Transaction would revert',
                    'reason': self._extract_revert_reason(error_msg)
                }
            return {'success': False, 'error': error_msg}
    
    def _estimate_l1_fee(self, transaction: Dict) -> int:
        """Estimate L1 data posting fee for Ethereum Mainnet"""
        
        # Serialize transaction to estimate size
        tx_data = self.w3.to_json(transaction)
        data_size = len(tx_data.encode('utf-8'))
        
        # Ethereum Mainnet formula approximation
        # L1 fee = data_size * l1_gas_price * scalar
        l1_gas_price = self.w3.eth.gas_price  # Use current L1 gas price
        scalar = 0.684  # Ethereum Mainnet scalar (this changes over time)
        
        l1_fee = int(data_size * 16 * l1_gas_price * scalar)
        return l1_fee
    
    def _extract_revert_reason(self, error_msg: str) -> str:
        """Extract revert reason from error message"""
        
        # Common patterns
        if 'insufficient balance' in error_msg.lower():
            return 'Insufficient balance'
        elif 'transfer amount exceeds allowance' in error_msg.lower():
            return 'Transfer amount exceeds allowance'
        elif 'transfer amount exceeds balance' in error_msg.lower():
            return 'Transfer amount exceeds balance'
        
        # Try to extract custom revert message
        if '0x08c379a0' in error_msg:
            # Standard revert string
            try:
                start = error_msg.index('0x08c379a0')
                hex_msg = error_msg[start:start+138]  # Standard length
                # Decode would go here
                return 'Contract reverted'
            except:
                pass
        
        return 'Unknown revert reason'
    
    def optimize_gas_settings(
        self,
        transaction: Dict,
        speed: str = 'standard'
    ) -> Dict[str, Any]:
        """Get optimized gas settings based on network conditions"""
        
        # Get current network state
        latest_block = self.w3.eth.get_block('latest')
        base_fee = latest_block['baseFeePerGas']
        
        # Get gas estimate
        gas_estimate = self.w3.eth.estimate_gas(transaction)
        
        # Speed presets
        presets = {
            'slow': {
                'buffer': 1.05,
                'priority_multiplier': 0.8
            },
            'standard': {
                'buffer': 1.1,
                'priority_multiplier': 1.0
            },
            'fast': {
                'buffer': 1.2,
                'priority_multiplier': 1.5
            },
            'instant': {
                'buffer': 1.3,
                'priority_multiplier': 2.0
            }
        }
        
        preset = presets.get(speed, presets['standard'])
        
        # Calculate optimized settings
        gas_limit = int(gas_estimate * preset['buffer'])
        max_priority_fee = int(
            self.w3.eth.max_priority_fee * preset['priority_multiplier']
        )
        max_fee_per_gas = base_fee * 2 + max_priority_fee
        
        # Calculate estimated cost
        estimated_cost = gas_limit * (base_fee + max_priority_fee)
        max_cost = gas_limit * max_fee_per_gas
        
        return {
            'speed': speed,
            'gas_limit': gas_limit,
            'max_fee_per_gas': max_fee_per_gas,
            'max_priority_fee_per_gas': max_priority_fee,
            'estimated_cost_eth': from_wei(estimated_cost, 'ether'),
            'max_cost_eth': from_wei(max_cost, 'ether'),
            'estimated_confirmation_time': self._estimate_confirmation_time(speed)
        }
    
    def _estimate_confirmation_time(self, speed: str) -> str:
        """Estimate confirmation time based on speed setting"""
        
        times = {
            'slow': '2-5 minutes',
            'standard': '15-30 seconds',
            'fast': '5-15 seconds',
            'instant': '< 5 seconds'
        }
        return times.get(speed, 'Unknown')
    
    def batch_estimate(self, transactions: List[Dict]) -> List[Dict[str, Any]]:
        """Estimate gas for multiple transactions"""
        
        results = []
        total_gas = 0
        total_cost = 0
        
        for i, tx in enumerate(transactions):
            try:
                gas_estimate = self.w3.eth.estimate_gas(tx)
                gas_price = self.w3.eth.gas_price
                cost = gas_estimate * gas_price
                
                results.append({
                    'index': i,
                    'gas_estimate': gas_estimate,
                    'cost_wei': cost,
                    'cost_eth': from_wei(cost, 'ether'),
                    'success': True
                })
                
                total_gas += gas_estimate
                total_cost += cost
                
            except Exception as e:
                results.append({
                    'index': i,
                    'error': str(e),
                    'success': False
                })
        
        return {
            'estimates': results,
            'summary': {
                'total_gas': total_gas,
                'total_cost_wei': total_cost,
                'total_cost_eth': from_wei(total_cost, 'ether'),
                'successful': len([r for r in results if r['success']]),
                'failed': len([r for r in results if not r['success']])
            }
        }

# Usage examples
calculator = GasCalculator(w3)

# Estimate ETH transfer
transfer_estimate = calculator.estimate_transfer(
    '0xFromAddress',
    '0xToAddress',
    0.1  # 0.1 ETH
)
print(f"Gas needed: {transfer_estimate['gas_limit']}")
print(f"Estimated cost: {transfer_estimate['estimated_cost_eth']} ETH")

# Estimate contract call
contract_estimate = calculator.estimate_contract_call(
    '0xFromAddress',
    '0xContractAddress',
    '0xa9059cbb000000000000000000000000....'  # transfer function data
)
print(f"Total cost: {contract_estimate['total_cost_eth']} ETH")

# Get optimized settings
optimized = calculator.optimize_gas_settings(
    {'from': '0xFrom', 'to': '0xTo', 'value': to_wei(0.1, 'ether')},
    speed='fast'
)
print(f"Optimized gas limit: {optimized['gas_limit']}")
print(f"Max fee: {optimized['max_fee_per_gas']} wei")

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 Type	Description	Solution
Execution reverted	Transaction would fail	Check contract requirements
Gas required exceeds limit	Block gas limit exceeded	Split into smaller transactions
Insufficient funds	Not enough ETH for gas	Add 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 Ethereum documentation.