eth_estimateGas

eth_estimateGas simulates a transaction against current Polygon state and returns the amount of gas it would consume — without ever broadcasting it. On Polygon PoS gas is paid in MATIC, and while fees are very low, an undersized gas limit still fails with out-of-gas, so estimating first is the safe path. Send the transaction object to https://polygon.therpc.io/YOUR_API_KEY (chain ID 137, 0x89) and the node runs the EVM, returning a hex gas figure that already includes a small safety buffer.

Use cases

• Calculate the gas limit to set on a Polygon transaction before signing — for example a USDT transfer to 0xc2132D05D31c914a87C6611C10748AEb04B58e8F.
• Estimate the deployment cost of a new contract on Polygon by omitting to and passing the bytecode in data.
• Check whether a transaction would succeed at the current head without spending any MATIC to find out.
• Drive live fee estimates in a Polygon wallet or dApp UI, combining the gas estimate with the current gas price.

Parameters

Response

Example request

1curl https://polygon.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 Polygon playground.

Errors & troubleshooting

Common pitfalls

• The estimate is not a hard guarantee — multiply by roughly 1.2 before setting the gas limit so an edge-case path does not run out of gas. On Polygon the extra MATIC headroom costs almost nothing.
• If the simulated transaction reverts, you get an error (code 3 or -32000), not a gas number — handle that path instead of expecting a figure.
• Gas usage can shift between estimation and inclusion if contract state changes in the interim, which on Polygon's ~2s blocks can happen within a couple of blocks. Re-estimate if the transaction sits unsent.

Supported networks

• Mainnet — Chain ID: 137
• Amoy — Chain ID: 80002

See also

• eth_call
• eth_sendRawTransaction
• eth_gasPrice
• eth_feeHistory

1curl https://polygon.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]}'