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 transactions
• Cost Estimation - Preview transaction fees for users
• Gas Optimization - Find optimal gas usage for complex operations
• Error Prevention - Detect transaction 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": "0xd46e8dd67c5d32be8058bb8eb970870f072244567",
      "value": "0x9184e72a",
      "data": "0xd46e8dd67c5d32be8058bb8eb970870f072445675"
    }
  ],
  "id": 1
}

Returns

QUANTITY - The estimated gas amount in hexadecimal.

• Type: Hexadecimal string
• Unit: Gas units
• Format: 0x prefixed
• Example: "0x5208" (21000 gas for simple transfer)

Implementation Examples

cURL

# Estimate gas for BERA transfer
curl -X POST https://api-berachain-mainnet.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_estimateGas",
    "params": [
      {
        "from": "0xb60e8dd61c5d32be8058bb8eb970870f07233155",
        "to": "0xd46e8dd67c5d32be8058bb8eb970870f072244567", 
        "value": "0xde0b6b3a7640000"
      }
    ],
    "id": 1
  }'

# Estimate gas for contract interaction
curl -X POST https://api-berachain-mainnet.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0", 
    "method": "eth_estimateGas",
    "params": [
      {
        "from": "0xUserAddress",
        "to": "0xContractAddress",
        "data": "0xa9059cbb000000000000000000000000RecipientAddress0000000000000000000000000000000000000000000000000de0b6b3a7640000"
      }
    ],
    "id": 1
  }'

JavaScript

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

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

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

  async estimateBeraTransfer(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 in BERA
      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(),
        estimatedCostBera: formatEther(estimatedCost),
        estimatedCostEIP1559Bera: formatEther(estimatedCostEIP1559)
      };
    } catch (error) {
      console.error('Gas estimation failed:', error);
      throw error;
    }
  }

  async estimateContractCall(contractAddress, data, from, value = '0') {
    const gasEstimate = await this.provider.estimateGas({
      from: from,
      to: contractAddress,
      data: data,
      value: parseEther(value)
    });

    const gasWithBuffer = gasEstimate * 120n / 100n; // 20% buffer for contracts
    return gasWithBuffer;
  }

  async estimateTokenTransfer(tokenAddress, from, to, amount) {
    // ERC-20 transfer function signature
    const transferSelector = '0xa9059cbb';
    const paddedTo = to.slice(2).padStart(64, '0');
    const paddedAmount = amount.toString(16).padStart(64, '0');
    const data = transferSelector + paddedTo + paddedAmount;

    return await this.estimateContractCall(tokenAddress, data, from);
  }
}

// Usage examples
const gasEstimator = new GasEstimator(provider);

// Estimate simple BERA transfer
const transferEstimate = await gasEstimator.estimateBeraTransfer(
  '0xFromAddress',
  '0xToAddress', 
  '1.0' // 1 BERA
);
console.log('Transfer cost:', transferEstimate.estimatedCostBera, 'BERA');

// Estimate contract interaction
const contractGas = await gasEstimator.estimateContractCall(
  '0xContractAddress',
  '0xFunctionCallData',
  '0xFromAddress'
);
console.log('Contract call gas:', contractGas.toString());

Python

import requests
import json
from web3 import Web3

def estimate_gas(transaction_object, block='latest'):
    url = 'https://api-berachain-mainnet.n.dwellir.com/YOUR_API_KEY'
    
    payload = {
        "jsonrpc": "2.0",
        "method": "eth_estimateGas", 
        "params": [transaction_object, block],
        "id": 1
    }
    
    response = requests.post(url, json=payload)
    data = response.json()
    
    if 'result' in data:
        gas_estimate = int(data['result'], 16)
        print(f"Gas estimate: {gas_estimate:,} units")
        return gas_estimate
    else:
        print(f"Error: {data.get('error', {}).get('message', 'Unknown error')}")
        return None

# Estimate BERA transfer
def estimate_bera_transfer(from_addr, to_addr, value_bera):
    value_wei = int(value_bera * 10**18)
    
    tx = {
        "from": from_addr,
        "to": to_addr,
        "value": hex(value_wei)
    }
    
    return estimate_gas(tx)

# Using web3.py
w3 = Web3(Web3.HTTPProvider('https://api-berachain-mainnet.n.dwellir.com/YOUR_API_KEY'))

def estimate_with_web3(from_addr, to_addr, value_bera, data=None):
    """Estimate gas using web3.py with detailed cost calculation"""
    
    tx_params = {
        'from': from_addr,
        'to': to_addr,
        'value': w3.to_wei(value_bera, 'ether')
    }
    
    if data:
        tx_params['data'] = data
    
    try:
        # Get gas estimate
        gas_estimate = w3.eth.estimate_gas(tx_params)
        
        # Get current gas price
        gas_price = w3.eth.gas_price
        
        # Calculate total cost
        total_cost_wei = gas_estimate * gas_price
        total_cost_bera = w3.from_wei(total_cost_wei, 'ether')
        
        print(f"Gas estimate: {gas_estimate:,} units")
        print(f"Gas price: {w3.from_wei(gas_price, 'gwei')} Gwei")
        print(f"Total cost: {total_cost_bera} BERA")
        
        return {
            'gas_estimate': gas_estimate,
            'gas_price': gas_price,
            'total_cost_wei': total_cost_wei,
            'total_cost_bera': float(total_cost_bera)
        }
        
    except Exception as e:
        print(f"Gas estimation failed: {e}")
        return None

# Estimate token transfer
def estimate_token_transfer(token_address, from_addr, to_addr, amount):
    """Estimate gas for ERC-20 token transfer"""
    
    # ERC-20 transfer function signature
    method_id = '0xa9059cbb'
    padded_to = to_addr[2:].zfill(64) 
    padded_amount = format(amount, '064x')
    data = method_id + padded_to + padded_amount
    
    tx = {
        "from": from_addr,
        "to": token_address,
        "data": data
    }
    
    return estimate_gas(tx)

Go

package main

import (
    "context"
    "fmt"
    "log"
    "math/big"
    
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/ethclient"
    "github.com/ethereum/go-ethereum"
)

func main() {
    client, err := ethclient.Dial("https://api-berachain-mainnet.n.dwellir.com/YOUR_API_KEY")
    if err != nil {
        log.Fatal(err)
    }
    
    // Estimate gas for BERA transfer
    fromAddr := common.HexToAddress("0xFromAddress")
    toAddr := common.HexToAddress("0xToAddress")
    value := big.NewInt(1000000000000000000) // 1 BERA in wei
    
    gasLimit, err := client.EstimateGas(context.Background(), ethereum.CallMsg{
        From:  fromAddr,
        To:    &toAddr,
        Value: value,
    })
    if err != nil {
        log.Fatal(err)
    }
    
    fmt.Printf("Gas estimate: %d units\n", gasLimit)
    
    // Get current gas price for cost calculation
    gasPrice, err := client.SuggestGasPrice(context.Background())
    if err != nil {
        log.Fatal(err)
    }
    
    totalCost := new(big.Int).Mul(big.NewInt(int64(gasLimit)), gasPrice)
    fmt.Printf("Estimated cost: %s wei\n", totalCost.String())
    
    // Convert to BERA
    costInBera := new(big.Float).Quo(new(big.Float).SetInt(totalCost), big.NewFloat(1e18))
    fmt.Printf("Estimated cost: %f BERA\n", costInBera)
}

// Estimate gas for contract interaction
func estimateContractCall(client *ethclient.Client, contractAddr, fromAddr common.Address, data []byte) (uint64, error) {
    gasEstimate, err := client.EstimateGas(context.Background(), ethereum.CallMsg{
        From: fromAddr,
        To:   &contractAddr,
        Data: data,
    })
    
    if err != nil {
        return 0, fmt.Errorf("gas estimation failed: %w", err)
    }
    
    // Add 20% buffer for contract calls
    gasWithBuffer := uint64(float64(gasEstimate) * 1.2)
    return gasWithBuffer, nil
}

// Estimate gas with retry logic
func safeEstimateGas(client *ethclient.Client, msg ethereum.CallMsg, maxRetries int) (uint64, error) {
    for i := 0; i < maxRetries; i++ {
        gasEstimate, err := client.EstimateGas(context.Background(), msg)
        if err == nil {
            return gasEstimate, nil
        }
        
        log.Printf("Gas estimation attempt %d failed: %v", i+1, err)
        
        if i == maxRetries-1 {
            return 0, err
        }
        
        // Simple retry delay
        time.Sleep(time.Second)
    }
    
    return 0, fmt.Errorf("gas estimation failed after %d attempts", maxRetries)
}

Response Example

Successful Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x5208"
}

Note: Result 0x5208 equals 21,000 gas units (standard for simple BERA transfers).

Error Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32000,
    "message": "insufficient funds for gas * price + value"
  }
}

Common Use Cases

1. Transaction Cost Preview

Show users estimated costs before confirming:

async function previewTransactionCost(from, to, value) {
  try {
    const gasEstimate = await provider.estimateGas({
      from: from,
      to: to, 
      value: parseEther(value)
    });
    
    const feeData = await provider.getFeeData();
    const totalCost = gasEstimate * feeData.gasPrice;
    
    return {
      gasUnits: gasEstimate.toString(),
      gasCostBera: formatEther(totalCost),
      totalCostBera: formatEther(totalCost + parseEther(value))
    };
  } catch (error) {
    return { error: error.message };
  }
}

2. Optimal Gas Limit Calculation

Calculate optimal gas limits with buffers:

async function calculateOptimalGas(txParams, bufferPercent = 20) {
  const baseEstimate = await provider.estimateGas(txParams);
  const gasWithBuffer = baseEstimate * BigInt(100 + bufferPercent) / 100n;
  
  // Cap at reasonable maximum
  const maxGas = 10000000n; // 10M gas limit
  const finalGas = gasWithBuffer > maxGas ? maxGas : gasWithBuffer;
  
  return {
    baseEstimate: baseEstimate.toString(),
    withBuffer: gasWithBuffer.toString(),
    recommended: finalGas.toString(),
    bufferPercent
  };
}

3. Contract Gas Analysis

Analyze gas usage for different contract methods:

async function analyzeContractGas(contractAddress, methods, from) {
  const gasAnalysis = {};
  
  for (const [methodName, data] of Object.entries(methods)) {
    try {
      const gas = await provider.estimateGas({
        from: from,
        to: contractAddress,
        data: data
      });
      
      gasAnalysis[methodName] = {
        gasEstimate: gas.toString(),
        estimatedCost: formatEther(gas * await provider.getGasPrice()),
        complexity: gas > 100000n ? 'high' : gas > 50000n ? 'medium' : 'low'
      };
    } catch (error) {
      gasAnalysis[methodName] = {
        error: error.message,
        gasEstimate: null
      };
    }
  }
  
  return gasAnalysis;
}

Performance Optimization

Gas Estimation Caching

Cache estimates for similar transactions:

class GasCache {
  constructor(ttl = 60000) { // 1 minute cache
    this.cache = new Map();
    this.ttl = ttl;
  }
  
  getCacheKey(txParams) {
    return JSON.stringify({
      from: txParams.from,
      to: txParams.to,
      data: txParams.data,
      value: txParams.value?.toString()
    });
  }
  
  async estimate(provider, txParams) {
    const key = this.getCacheKey(txParams);
    const cached = this.cache.get(key);
    
    if (cached && Date.now() - cached.timestamp < this.ttl) {
      return cached.gas;
    }
    
    const gas = await provider.estimateGas(txParams);
    this.cache.set(key, { gas, timestamp: Date.now() });
    
    return gas;
  }
  
  invalidate(txParams = null) {
    if (txParams) {
      const key = this.getCacheKey(txParams);
      this.cache.delete(key);
    } else {
      this.cache.clear();
    }
  }
}

const gasCache = new GasCache();

Batch Gas Estimation

Estimate gas for multiple transactions:

async function batchGasEstimate(transactions) {
  const batch = transactions.map((tx, index) => ({
    jsonrpc: '2.0',
    method: 'eth_estimateGas',
    params: [tx],
    id: index + 1
  }));
  
  const response = await fetch('https://api-berachain-mainnet.n.dwellir.com/YOUR_API_KEY', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(batch)
  });
  
  const results = await response.json();
  return results.map((result, index) => ({
    transaction: transactions[index],
    gasEstimate: result.error ? null : parseInt(result.result, 16),
    error: result.error?.message
  }));
}

Error Handling

Common errors and solutions:

Error Code	Description	Solution
-32000	Insufficient funds	Check account balance
-32016	Invalid block number	Use valid block parameter
3	Execution reverted	Check contract logic and parameters
-32602	Invalid params	Verify transaction object format

async function safeEstimateGas(txParams, maxRetries = 3) {
  // Validate transaction parameters
  if (!txParams.to) {
    throw new Error('Transaction must have a "to" address');
  }
  
  for (let i = 0; i < maxRetries; i++) {
    try {
      const gasEstimate = await provider.estimateGas(txParams);
      return gasEstimate;
    } catch (error) {
      console.error(`Gas estimation attempt ${i + 1} failed:`, error.message);
      
      if (error.code === 3) {
        // Execution reverted - don't retry
        throw new Error(`Transaction would revert: ${error.message}`);
      }
      
      if (error.code === -32000) {
        // Insufficient funds - don't retry
        throw new Error(`Insufficient funds: ${error.message}`);
      }
      
      if (i === maxRetries - 1) {
        throw error;
      }
      
      // Exponential backoff for retryable errors
      await new Promise(r => setTimeout(r, Math.pow(2, i) * 1000));
    }
  }
}

// Usage with comprehensive error handling
try {
  const gasEstimate = await safeEstimateGas({
    from: senderAddress,
    to: recipientAddress,
    value: parseEther('1.0'),
    data: contractCallData
  });
  
  console.log('Safe gas estimate:', gasEstimate.toString());
} catch (error) {
  console.error('Gas estimation failed:', error.message);
  // Handle error appropriately in your application
}

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