eth_estimateGas - World Chain RPC Method

Estimates the gas necessary to execute a transaction on World Chain.

Why World Chain? Build on the human-first Ethereum L2 powered by World ID with World ID integration for free gas and priority blockspace.

When to Use This Method

The eth_estimateGas method serves these key scenarios for World Chain developers building sybil-resistant applications:

• Calculate gas budgets - Determine how much gas a transaction requires before submitting, helping set accurate gas limits for human-verified DeFi, identity-gated applications, bot-resistant services
• Estimate costs for complex interactions - Predict gas requirements for multi-step contract calls, such as DeFi composability chains across multiple protocols
• Compare gas efficiency - Evaluate gas consumption between different contract implementations to identify the most cost-effective approach on World Chain
• Prevent out-of-gas failures - Verify that the gas limit is sufficient for the intended transaction to avoid wasted gas on reverted transactions

Common Use Cases

1. Estimate Gas for an ERC20 Transfer

Before sending an ERC20 transfer, estimate the gas cost to ensure you set a sufficient limit. Token transfers typically consume more gas than native ETH transfers because they execute contract logic - most ERC20 implementations use around 45,000-65,000 gas per transfer.

import { JsonRpcProvider, Contract } from 'ethers';

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

const erc20Abi = [
  'function transfer(address to, uint256 amount) returns (bool)'
];
const tokenContract = new Contract('0x4200000000000000000000000000000000000006', erc20Abi, provider);

async function estimateTransferGas(to, amount) {
  const gasEstimate = await tokenContract.transfer.estimateGas(to, amount);
  console.log('Estimated gas for transfer:', gasEstimate.toString());
  return gasEstimate;
}

const gas = await estimateTransferGas('0x4200000000000000000000000000000000000006', '1000000000000000000');

2. Simulate Contract Deployment Cost

Estimate how much gas a contract deployment will consume before submitting the creation transaction. The deployment cost depends on the bytecode size and constructor arguments - use this to budget for contract deployments on World Chain.

import { JsonRpcProvider, ContractFactory } from 'ethers';

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

async function estimateDeploymentGas(bytecode, abi, constructorArgs) {
  const factory = new ContractFactory(abi, bytecode, provider);
  const deployTx = await factory.getDeployTransaction(...constructorArgs);
  const gasEstimate = await provider.estimateGas(deployTx);
  console.log('Estimated deployment gas:', gasEstimate.toString());
  return gasEstimate;
}

const estimatedGas = await estimateDeploymentGas(
  '0x608060...',
  ['constructor(uint256)'],
  [42]
);

3. Build Transaction with Gas Buffer

Apply a safety buffer to the estimated gas to account for minor state changes between estimation and execution. The recommended buffer varies by chain - fast, low-congestion chains like World Chain may need only 20%, while complex DeFi interactions benefit from 50%.

import { JsonRpcProvider, parseEther } from 'ethers';

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

async function buildSafeTransaction(from, to, value, contractData) {
  const [nonce, feeData] = await Promise.all([
    provider.getTransactionCount(from),
    provider.getFeeData()
  ]);

  const tx = {
    from,
    to,
    value: parseEther(value),
    data: contractData || '0x',
    nonce,
    maxFeePerGas: feeData.maxFeePerGas,
    maxPriorityFeePerGas: feeData.maxPriorityFeePerGas
  };

  const estimatedGas = await provider.estimateGas(tx);
  const bufferRatio = contractData ? 1.5 : 1.2;
  tx.gasLimit = BigInt(Math.floor(Number(estimatedGas) * bufferRatio));

  console.log('Estimated gas:', estimatedGas.toString());
  console.log('Buffered gas limit:', tx.gasLimit.toString());
  return tx;
}

const tx = await buildSafeTransaction(
  '0x4200000000000000000000000000000000000006',
  '0x4200000000000000000000000000000000000006',
  '0.01'
);

Best Practices

• Add a 20-50% buffer to the estimated gas value for safety: simple transfers need less buffer, complex contract calls need more
• If the estimate reverts, the transaction would also revert: fix the underlying issue rather than increasing gas
• eth_estimateGas runs against the current state at block latest: state changes between estimation and execution can alter the actual gas requirement
• For EIP-1559 chains, combine eth_estimateGas with eth_feeHistory to calculate the accurate total transaction cost in native currency
• L2 chains may return significantly different gas estimates than L1 for the same contract interaction

Code Examples

Error Handling

Tip: If estimation fails, the transaction would likely revert if sent.

Related Methods

• eth_gasPrice - Get current gas price
• eth_sendRawTransaction - Send transaction