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. Note that the estimate may be significantly more than the amount of gas actually used by the transaction, for a variety of reasons including EVM mechanics and node performance.

Method Limitations

To prevent abuse of the API, the gas parameter to eth_estimateGas and eth_call are capped at 10x (1000%) the current block gas limit. You can recreate this behavior in your local test environment (ganache, besu, geth, or other client) via the rpc.gascap command-line option.

REQUEST

POST https://<network>.chainrpc.io/v3/YOUR-API-KEY

HEADERS

Content-Type: application/json

REQUEST PAYLOAD

• TRANSACTION CALL OBJECT [required]

  • from: [optional] 20 Bytes - The address the transaction is sent from.

  • to: 20 Bytes - The address the transaction is directed to.

  • gas: [optional] hexadecimal value of the gas provided for the transaction execution. eth_estimateGas consumes zero gas, but this parameter may be needed by some executions.

  • gasPrice: [optional] hexadecimal value of the gasPrice used for each paid gas.

  • maxPriorityFeePerGas: [optional] Maximum fee, in Wei, the sender is willing to pay per gas above the base fee. See EIP-1559 transactions.

  • maxFeePerGas: [optional] Maximum total fee (base fee + priority fee), in Wei, the sender is willing to pay per gas. See EIP-1559 transactions.

  • value: [optional] hexadecimal value of the value sent with this transaction.

  • data: [optional] Hash of the method signature and encoded parameters. See the Ethereum contract ABI specification.

If no gas limit is specified, geth uses the block gas limit from the pending block as an upper bound. As a result the returned estimate might not be enough to executed the call/transaction when the amount of gas is higher than the pending block gas limit.

EXAMPLE

## JSON-RPC over HTTPS POST
## Replace YOUR-API-KEY with an API key from your chainRPC Dashboard
## You can also replace mainnet with a different supported network
curl https://eth.chainrpc.io/v3/YOUR-API-KEY \
    -X POST \
    -H "Content-Type: application/json" \
    -d '{"jsonrpc":"2.0","method":"eth_estimateGas","params": [{"from": "0xb60e8dd61c5d32be8058bb8eb970870f07233155","to": "0xd46e8dd67c5d32be8058bb8eb970870f07244567","gas": "0x76c0","gasPrice": "0x9184e72a000","value": "0x9184e72a","data": "0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675"}],"id":1}'

## JSON-RPC over WSS
## Replace YOUR-API-KEY with an API key from your Infura Dashboard
## You can also replace mainnet with a different supported network
wscat -c wss://eth.chainrpc.io/v3/YOUR-API-KEY
>{"jsonrpc":"2.0","method":"eth_estimateGas","params": [{"from": "0xb60e8dd61c5d32be8058bb8eb970870f07233155","to": "0xd46e8dd67c5d32be8058bb8eb970870f07244567","gas": "0x76c0","gasPrice": "0x9184e72a000","value": "0x9184e72a","data": "0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675"}],"id":1}

RESPONSE

RESULT FIELDS

• GAS USED - the amount of gas used.

BODY

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x5cec"
}

On Mainnet, Rinkeby, Ropsten, and Goerli, if this call causes the EVM to execute a REVERT operation, an error response of the following form is returned, with the revert reason pre-decoded as a string (not yet supported on Kovan):

{
    "jsonrpc": "2.0",
    "id": 1,
    "error": {
        "code": 3,
        "message": "execution reverted: Dai/insufficient-balance",
        "data": "0x08c379a0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000184461692f696e73756666696369656e742d62616c616e63650000000000000000"
    }
}