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.

Parameters

1. Object — Transaction call object (same as eth_call):

   Field	Type	Required	Description
   from	DATA	No	Sender address
   to	DATA	No	Recipient address
   gas	QUANTITY	No	Gas limit
   gasPrice	QUANTITY	No	Gas price
   value	QUANTITY	No	Value in wei
   data	DATA	No	Call data

2. QUANTITY|TAG — (Optional) Block number, or "latest".

Returns

QUANTITY — The estimated amount of gas.

Request

curl -X POST https://eth-mainnet.blockreq.com/v1/rpc/public \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_estimateGas",
    "params": [{
      "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
      "to": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
      "value": "0x0",
      "data": "0xa9059cbb0000000000000000000000001234567890abcdef1234567890abcdef1234567800000000000000000000000000000000000000000000000000000000000f4240"
    }],
    "id": 1
  }'

Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0xc350"
}

Code Examples

JavaScript (ethers.js v6)

import { JsonRpcProvider } from "ethers";
const provider = new JsonRpcProvider("https://eth-mainnet.blockreq.com/v1/rpc/YOUR_API_KEY");
const gas = await provider.estimateGas({
  to: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
  data: "0xa9059cbb..."
});
console.log("Estimated gas:", gas.toString());

Python (web3.py)

from web3 import Web3
w3 = Web3(Web3.HTTPProvider("https://eth-mainnet.blockreq.com/v1/rpc/YOUR_API_KEY"))
gas = w3.eth.estimate_gas({
    "to": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    "data": "0xa9059cbb..."
})
print(f"Estimated gas: {gas}")

RU Cost

Method	Cost
eth_estimateGas	20 RU