RPC method

eth_estimateGas on Core

Supported on SwiftNodes

Everything below was measured on 2026-10-13 by calling eth_estimateGas on Core through the same endpoint customers use, and is re-measured weekly.

What eth_estimateGas does

Runs a transaction against current state and returns the gas it would use, so you can set a gas limit. If the transaction would revert or the sender cannot pay, the node returns an error instead of a number.

eth_estimateGas on Core: what we measured

Zero-value CORE transfer to an EOA	21,000 gas
Same on Ethereum	21,000 gas
1 wei from an empty account	failed with 50000000 gas: insufficient funds for gas * price + value: address 0xD1d5499e3b1a1a00d3162f2170eE2d69B5Fd5d1E have 0 want 1

What the numbers mean

A plain transfer estimates at exactly 21,000 gas on Core, as on Ethereum. Contract calls vary with state, so estimate those rather than hard-coding a limit.

An estimate for a sender that cannot pay fails with: "failed with 50000000 gas: insufficient funds for gas * price + value: address 0xD1d5499e3b1a1a00d3162f2170eE2d69B5Fd5d1E have 0 want 1". Your app sees this text when a user's balance is too low, so match on it to show a clear message.

Chains where a transfer is not 21,000 gas

Of the 53 chains we measure, 6 estimate a plain transfer at something other than 21,000 gas.

Example request

curl -s https://rpc.swiftnodes.io/rpc/core?key=YOUR_API_KEY \
  -X POST -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_estimateGas","params":[{"from":"0x0000000000000000000000000000000000000000","to":"0x000000000000000000000000000000000000dEaD","value":"0x0"}]}'

import { createPublicClient, http } from "viem";

const client = createPublicClient({
  transport: http("https://rpc.swiftnodes.io/rpc/core?key=YOUR_API_KEY"),
});

const gas = await client.estimateGas({ account: from, to, value });
// Add headroom: state can change between estimate and inclusion
const gasLimit = (gas * 120n) / 100n;

Other methods on Core

eth_estimateGas on other chains

Frequently asked questions

Does Core support eth_estimateGas?

Yes. eth_estimateGas answered on the SwiftNodes Core endpoint when our weekly probe called it through the customer path (2026-10-13).

How much gas does a plain transfer use on Core?

eth_estimateGas returned 21,000 for a plain transfer on 2026-10-13.

What does "insufficient funds for gas * price + value" mean from eth_estimateGas on Core?

The sender's balance cannot cover the value plus the gas. Fund the account or lower the value; the have and want figures in the message are in wei.

Core endpoints, live block height and WebSocket status are on the Core RPC page.

One key covers every chain we serve, and SwiftNodes has a free tier.