ETH Gas Fee Calculator

How Ethereum gas fees are calculated

Every transaction pays gas limit times gas price. The gas limit measures how much computation the transaction performs, and since EIP-1559 the gas price has two parts: a base fee that the protocol sets each block and burns, and a priority fee you add as a tip so block builders include you sooner. Your wallet submits a max fee per gas that caps the total; whatever the transaction does not use is refunded. Gas prices are quoted in gwei, which is a billionth of an ETH, so a transfer of 21,000 gas at 20 gwei costs 0.00042 ETH. If you need to move between gwei, wei and ETH, the unit converter does exact big-integer math.

The gas limit depends on what the transaction does, and the values below are what the calculator uses for its presets. Real usage varies with the contract, the token and the state it touches, so treat them as typical figures rather than exact ones.

Why fees change block to block

The base fee reacts to demand every 12 seconds. Blocks target 50% fullness; a fuller block raises the next base fee by up to 12.5% and an emptier one lowers it by the same amount, which compounds fast in both directions. On top of that, the priority fee market is a live auction inside the mempool, and it is where the tiers above come from: this page reads the base fee of the latest block and the distribution of tips that pending transactions are actually offering, straight from BLAZED's own Ethereum node. Slow rides the 25th percentile of those tips, standard the median, fast the 75th and rapid the 90th.

That also explains why a fee that looked fine when you signed can leave a transaction stuck. The base fee is not a bid; it is whatever the next block demands, and a max fee below it means no builder can include you at all until demand falls back. Setting a generous max fee costs nothing when the network is quiet, because the difference is refunded, and it is the difference between confirming and waiting when the network is not.

Reading gas prices from code

A wallet screen is fine for one transaction; a bot needs the numbers programmatically. Four JSON-RPC methods cover it. eth_gasPrice returns a single legacy figure, eth_maxPriorityFeePerGas a suggested tip, eth_feeHistory the base fee and tip percentiles across recent blocks, and eth_estimateGas the gas limit for a specific call. The tiers on this page are built from the third of those. In ethers.js the first three collapse into one call:

import { WebSocketProvider } from "ethers";

// Inside a BLAZED.sh container or script this is the co-located node.
const provider = new WebSocketProvider("ws://eth:8545");

const fee = await provider.getFeeData();
// fee.gasPrice, fee.maxFeePerGas, fee.maxPriorityFeePerGas (bigint, wei)

const gas = await provider.estimateGas({ to: recipient, value: amount });
const worstCase = gas * fee.maxFeePerGas; // wei you could pay

If your application needs this continuously, polling a third-party gas API adds latency exactly when fees move fastest, and the number you get is a cache of a number that has already changed. BLAZED.sh runs your container or script directly on the node, so you read the mempool and every new block over local IPC in under 10 milliseconds instead of waiting on someone else's HTTP hop. Each call draws a predictable per-request credit rather than an opaque compute unit, and the JSON-RPC method reference documents what each one returns. One more habit worth keeping before you sign anything: run the recipient through the EIP-55 address checker, because a fee you got right on an address you got wrong is still a total loss.

Frequently asked questions