eth_estimateGas on Ethereum
Simulates a transaction and returns the gas it would consume, without broadcasting it. Wallets call this before signing to set a sensible gas limit.
It simulates once at current state, so a tx whose cost depends on other pending txs can be under-estimated — pad the result (e.g. +20%). On L2s the figure covers L2 execution only; the L1 data fee is added at inclusion.
Ethereum endpoint (public — no key)
https://rpc.nodeflare.app/eth/publicMethod
eth_estimateGas
Cost
5 CU
Chain ID
1
Block time
~12 s
Finality
~13 min (finalized)
Contract calls on Ethereum
eth_call and eth_estimateGas execute against latest by default. Base fee moves up to 12.5% per block, so re-estimate close to submission if a transaction may sit in a queue.
Parameters
[callObject]cURL
curl https://rpc.nodeflare.app/eth/public \
-X POST \
-H 'content-type: application/json' \
-d '{"jsonrpc":"2.0","method":"eth_estimateGas","params":[{"to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48", "data": "0x18160ddd"}],"id":1}'The example targets the USDC contract on Ethereum — you can run it as-is.
ethers.js
import { ethers } from 'ethers';
const provider = new ethers.JsonRpcProvider(
'https://rpc.nodeflare.app/eth/public'
);
const result = await provider.send('eth_estimateGas', [{"to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48", "data": "0x18160ddd"}]);Try it live
Runs the example above against the public Ethereum endpoint — straight from your browser.
eth_estimateGas on Ethereum — FAQ
How do I call eth_estimateGas on Ethereum?
POST a JSON-RPC 2.0 request with "method": "eth_estimateGas" to NodeFlare's Ethereum endpoint at https://rpc.nodeflare.app/eth/public. No API key is required for the public endpoint.
What does eth_estimateGas cost on the free tier?
eth_estimateGas is weighted at 5 compute units per call. The free tier includes 2,000,000 CU/month, so that is roughly 400,000 eth_estimateGas calls per month — no credit card.
Is eth_estimateGas available on the public Ethereum endpoint?
Yes. eth_estimateGas works on the public Ethereum endpoint (https://rpc.nodeflare.app/eth/public) with no API key, rate-limited per IP. A free key adds higher limits and a dedicated path.
Anything Ethereum-specific to know when using eth_estimateGas?
eth_call and eth_estimateGas execute against latest by default. Base fee moves up to 12.5% per block, so re-estimate close to submission if a transaction may sit in a queue.
Call eth_estimateGas on Ethereum with a free key
2,000,000 compute units/month, heavy methods unlocked, every chain included. No credit card.
Get your free API key →eth_estimateGas on other chains