septim forge · free tool · ethereum fee calculator

Know Your Ethereum Fee Before You Send

live prices · L1 + L2 comparison · no wallet · no login

Read-only tool. Estimates only — not real-time guarantees. This page makes two network calls on load — the current gas price (pulled from multiple backup sources so the page always loads, even if one source is temporarily down) and the ETH/USD rate (CoinGecko free tier). Both are cached for 60 seconds and auto-refresh. Switching network re-fetches gas for that chain. No wallet connection. No transaction construction. All math runs in the browser. Gas unit values are typical historical figures; actual cost varies with contract state, calldata size, and network congestion. Verify on Etherscan or your wallet before submitting any real transaction.
// configure estimate
Network
Operation type
Sum gas cost across N transactions of the same type. Useful for batch workflows or DCA scripts.
// ethereum l1
$0.00
0.000000 ETH
// same operation on each network
Gas estimates are typical values based on historical Ethereum transaction data. Actual gas varies with contract state, calldata size, and network conditions. Verify on Etherscan before submitting any real transaction.
// what this page actually does on the network

Two fetches on open. Nothing else.

// verify in devtools

Open DevTools (F12 or Cmd+Option+I), go to the Network tab, then reload this page. You will see up to two requests on load: one JSON-RPC POST to a free public Ethereum RPC (no API key required) for the current gas price, and one GET to api.coingecko.com/api/v3/simple/price (CoinGecko free tier, no API key required) for the ETH/USD rate. The gas RPC tries up to three endpoints in order and stops at the first success. Both results are cached for 60 seconds and auto-refresh. Switching network re-fetches gas from that chain's RPC list. After the page loads: zero requests fire when you change form fields or click "Calculate cost." All math runs in the browser. If all RPCs fail, the last cached value is shown with its age, and the field stays editable.

// gas unit reference

Typical gas units by operation type

Every Ethereum transaction consumes a fixed minimum of 21,000 gas for the base transfer. Everything on top of that pays for EVM computation and storage writes. These are typical values — the real cost can vary by 10–30% depending on contract state.

OperationTypical gas unitsNotes
ETH transfer21,000Fixed. No contract call, no calldata. Always exactly 21,000 gas.
ERC-20 transfer~65,000Reads two storage slots (from/to balances), writes two slots. Varies by token: fee-on-transfer tokens cost more.
Uniswap v3 swap~185,000Includes tick crossing logic, position math, and two token transfers. V2 swaps are ~150,000 (no tick math).
ERC-721 NFT mint~80,000–250,000Wide range: a bare ERC-721 mint is ~80,000; Azuki-style contracts with merkle proofs and supply tracking run much higher.
Contract deploy~300,000–3,000,000Proportional to bytecode size. A simple token contract: ~300,000. A full AMM: 1–3M+. Estimate uses 500,000 as a moderate baseline.
// base fee + priority fee

What "gas price" actually means post-EIP-1559

Since EIP-1559 (August 2021), Ethereum gas pricing has two components. This tool presents the combined effective gas price as a single gwei value for simplicity — which is what you see on gas trackers and what your wallet sends.

Base fee — burned by the protocol, algorithmically adjusted every block to target 50% block utilization. When blocks are full, it rises; when blocks are empty, it falls. You cannot pay less than the base fee or your transaction won't be included.

Priority fee (tip) — paid to the validator. During low-congestion periods, 1–2 gwei is sufficient. During high-demand periods (NFT drops, DeFi liquidations), tips of 20–100+ gwei compete for block inclusion.

Effective gas price — base fee + priority fee = what you actually pay. The eth_gasPrice RPC method returns this combined value, which is what this tool fetches and displays.
// building on ethereum or an l2?

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