eth_estimateGas

eth_estimateGas simulates a transaction on Arbitrum One and returns the amount of gas it would need to execute on-chain, denominated in the units that ultimately cost ETH. On this Nitro-based Optimistic Rollup the figure reflects the combined cost model: L2 execution plus the L1 calldata the rollup must post to Ethereum, which ArbOS folds into the gas accounting. Send the simulation to https://arbitrum.therpc.io/YOUR_API_KEY (chain ID 42161) to size a transaction's gas limit before you sign it.

Use cases

• Calculate the gas limit to set on a transaction before signing and submitting it to the Arbitrum One sequencer.
• Estimate the cost of deploying a new contract, where the L1 calldata component of Arbitrum's fee can dominate.
• Check whether a swap or transfer would succeed without spending ETH — a revert during estimation flags the problem early.
• Drive fee estimates in a wallet or dApp UI so users see an accurate ETH cost for an Arbitrum One action.

Parameters

Response

Example request

1curl https://arbitrum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_estimateGas",
7    "params": [
8        {
9          "to": "0x0000000000000000000000000000000000000000",
10          "data": "0x"
11        },
12        "latest"
13      ],
14    "id": 1
15  }'

Try it live in the Arbitrum One playground.

Errors & troubleshooting

Common pitfalls

• The estimate is not a hard guarantee — pad the gas limit (e.g. ×1.2) to absorb edge cases, and remember Arbitrum's L1 calldata component can swing the figure as the underlying L1 base fee moves.
• If the simulation reverts, the method returns an error instead of a gas figure — handle that path rather than assuming a number always comes back.
• Gas usage can change between estimation and execution if contract state shifts in the interim; re-estimate close to submission for state-sensitive GMX or Aave actions.

Supported networks

• Mainnet — Chain ID: 42161
• Sepolia — Chain ID: 421614

See also

• eth_call
• eth_sendRawTransaction
• eth_gasPrice
• eth_feeHistory

1curl https://arbitrum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_estimateGas","params":[{"to":"0x0000000000000000000000000000000000000000","data":"0x"},"",null]}'