# eth_estimateGas - Arbitrum RPC Method

Estimates the gas necessary to execute a transaction on Arbitrum.

> **Why Arbitrum?** Build on Ethereum's leading Layer 2 with 46% L2 market share and $12B+ TVL with full EVM compatibility, 1.5M daily transactions, and $3B+ DAO treasury for ecosystem growth.

## When to Use This Method

The `eth_estimateGas` method serves these key scenarios for DeFi developers, protocol teams, and dApp builders seeking Ethereum scalability:

- **Calculate gas budgets** - Determine how much gas a transaction requires before submitting, helping set accurate gas limits for high-volume DeFi (GMX, Uniswap, Aave), gaming, and cross-chain applications
- **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 Arbitrum
- **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.

```javascript
import { JsonRpcProvider, Contract } from 'ethers';

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

const erc20Abi = [
  'function transfer(address to, uint256 amount) returns (bool)'
];
const tokenContract = new Contract('0x13867a801e352e219c2d2AC29288Bf086e5C81ef', 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('0x13867a801e352e219c2d2AC29288Bf086e5C81ef', '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 Arbitrum.

```javascript
import { JsonRpcProvider, ContractFactory } from 'ethers';

const provider = new JsonRpcProvider('https://api-arbitrum-mainnet-archive.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 Arbitrum may need only 20%, while complex DeFi interactions benefit from 50%.

```javascript
import { JsonRpcProvider, parseEther } from 'ethers';

const provider = new JsonRpcProvider('https://api-arbitrum-mainnet-archive.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(
  '0x13867a801e352e219c2d2AC29288Bf086e5C81ef',
  '0x13867a801e352e219c2d2AC29288Bf086e5C81ef',
  '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

## Request Parameters

- `from` (`DATA, optional`): Sender address
- `to` (`DATA, optional`): Recipient address
- `gas` (`QUANTITY, optional`): Gas limit
- `gasPrice` (`QUANTITY, optional`): Gas price
- `value` (`QUANTITY, optional`): Value in wei
- `data` (`DATA, optional`): Transaction data

## Request Example

```json
{
  "jsonrpc": "2.0",
  "method": "eth_estimateGas",
  "params": [{
    "from": "0x13867a801e352e219c2d2AC29288Bf086e5C81ef",
    "to": "0x13867a801e352e219c2d2AC29288Bf086e5C81ef",
    "value": "0x1"
  }],
  "id": 1
}
```

## Response Fields

- `result` (`QUANTITY, required`): Estimated gas amount in hexadecimal

## Successful Response

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

## Code Examples

cURL
JavaScript
Python
Go

```bash
curl -X POST https://api-arbitrum-mainnet-archive.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_estimateGas",
    "params": [{
      "from": "0x13867a801e352e219c2d2AC29288Bf086e5C81ef",
      "to": "0x13867a801e352e219c2d2AC29288Bf086e5C81ef",
      "value": "0x1"
    }],
    "id": 1
  }'
```

```javascript
import { JsonRpcProvider, parseEther } from 'ethers';

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

// Estimate simple transfer
async function estimateTransfer(to, value) {
  const gasEstimate = await provider.estimateGas({
    to: to,
    value: parseEther(value)
  });

  console.log('Estimated gas:', gasEstimate.toString());
  return gasEstimate;
}

// Estimate contract call
async function estimateContractCall(contract, method, args) {
  const gasEstimate = await contract[method].estimateGas(...args);
  console.log('Estimated gas:', gasEstimate.toString());

  // Add 20% buffer for safety
  return gasEstimate * 120n / 100n;
}
```

```python
from web3 import Web3

w3 = Web3(Web3.HTTPProvider('https://api-arbitrum-mainnet-archive.n.dwellir.com/YOUR_API_KEY'))

def estimate_transfer(to, value_in_ether):
    gas_estimate = w3.eth.estimate_gas({
        'to': to,
        'value': w3.to_wei(value_in_ether, 'ether')
    })

    print(f'Estimated gas: {gas_estimate}')
    return gas_estimate

def estimate_contract_call(contract, method, args):
    func = getattr(contract.functions, method)
    gas_estimate = func(*args).estimate_gas()

    # Add 20% buffer
    return int(gas_estimate * 1.2)

# Estimate simple transfer
gas = estimate_transfer('0x13867a801e352e219c2d2AC29288Bf086e5C81ef', 0.1)
```

```go
package main

import (
    "context"
    "fmt"
    "log"
    "math/big"

    "github.com/ethereum/go-ethereum"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/ethclient"
)

func main() {
    client, err := ethclient.Dial("https://api-arbitrum-mainnet-archive.n.dwellir.com/YOUR_API_KEY")
    if err != nil {
        log.Fatal(err)
    }

    toAddress := common.HexToAddress("0x13867a801e352e219c2d2AC29288Bf086e5C81ef")
    msg := ethereum.CallMsg{
        To:    &toAddress,
        Value: big.NewInt(1000000000000000000),
    }

    gasLimit, err := client.EstimateGas(context.Background(), msg)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Printf("Estimated gas: %d\n", gasLimit)
}
```

## Related Methods

- [`eth_gasPrice`](https://www.dwellir.com/docs/arbitrum/eth_gasPrice) - Get current gas price
- [`eth_sendRawTransaction`](https://www.dwellir.com/docs/arbitrum/eth_sendRawTransaction) - Send transaction