What is the difference between max fee and max priority fee?

Max priority fee per gas is the tip you offer validators on top of the base fee. Max fee per gas is the absolute most you are willing to pay per gas, covering both base fee and tip. The protocol charges base fee plus tip, never more than your max fee.

How is the effective gas price determined?

The effective gas price is the smaller of your max fee per gas, or the base fee plus your max priority fee. If the base fee plus your tip is below your max fee, you pay exactly that; if it would exceed your max fee, you are capped at the max fee and your effective tip shrinks.

What does it mean that the base fee is burned?

Since the London hard fork, the base fee portion of every transaction is destroyed (burned) rather than paid to validators. Only the priority fee (tip) goes to the validator. Burning the base fee makes ETH deflationary when network demand is high.

Why might I get a refund?

If you set a max fee well above the actual base fee, you are only charged the effective price, not your maximum. The difference between your max fee times gas and the amount actually charged is never deducted — it is effectively refunded by simply not being spent.

What if max fee is below base fee plus tip?

Then your transaction cannot pay your full requested tip. The validator receives whatever is left after the base fee, which may be less than your max priority fee. If max fee is below the base fee itself, the transaction is invalid and will not be included.

What is the EIP-1559 Transaction Fee Calculator?

Input base fee, max priority fee per gas, max fee per gas, and gas limit to compute the effective fee actually paid, the burned base fee, the validator tip, and the unused refund. Validates that maxFeePerGas is at least baseFee plus maxPriorityFeePerGas. For developers and DeFi users. It runs free in your browser on Gera Tools, with nothing uploaded.

EIP-1559 Transaction Fee Calculator

Name: EIP-1559 Transaction Fee Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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EIP-1559 changed how Ethereum prices transactions: instead of a single gas price, you specify a max fee and a max priority fee, and the protocol works out what you actually pay. This calculator implements that logic exactly — computing the effective gas price, the burned base fee, the validator tip, the total cost, and any unspent refund — and warns you if your max fee is set too low.

What EIP-1559 replaced and why it was introduced

Before the London hard fork (August 2021), Ethereum used a first-price auction: you bid a gas price, miners picked the highest bids, and you either paid your full bid or got stuck waiting. This made fee estimation unpredictable — you had to guess what others were bidding, and during congestion users often massively overbid to ensure inclusion.

EIP-1559 introduced a base fee — a protocol-set price per gas that adjusts automatically based on how full the previous block was (targeting 50% capacity). You now set two values: a cap on total price (maxFeePerGas) and a tip to incentivize validators above the base fee (maxPriorityFeePerGas). The protocol ensures you never pay more than your max fee.

An additional economic change: the base fee is burned, not paid to validators. This makes ETH supply deflationary when demand is high enough (when burned exceeds issued), which was a major design goal.

How it works

The protocol caps your effective gas price and splits it into a burned and a tipped portion:

effective gas price = min(maxFeePerGas, baseFee + maxPriorityFeePerGas)
effective tip       = effective gas price − baseFee   (≥ 0)
burned per gas      = baseFee
total fee (ETH)     = effective gas price × gasLimit / 1e9
burned (ETH)        = baseFee × gasLimit / 1e9
tip to validator    = effective tip × gasLimit / 1e9
refund (ETH)        = (maxFeePerGas − effective price) × gasLimit / 1e9

All gas-price values are in gwei (1 gwei = 0.000000001 ETH), so dividing by 10⁹ converts to ETH.

Worked example

Base fee: 25 gwei, max priority fee: 2 gwei, max fee: 40 gwei, gas limit: 21,000 (standard ETH transfer):

Effective gas price = min(40, 25+2) = 27 gwei
Burned per gas      = 25 gwei
Tip per gas         = 2 gwei
Total cost          = 27 × 21,000 / 1e9 = 0.000567 ETH
Burned              = 25 × 21,000 / 1e9 = 0.000525 ETH
Tip to validator    =  2 × 21,000 / 1e9 = 0.000042 ETH
Refund from max fee = (40−27) × 21,000 / 1e9 = 0.000273 ETH (not spent)

The 13 gwei of headroom between the effective price (27) and your max fee (40) is simply not charged — it is the safety buffer you set to protect against a base fee spike during the time your transaction is being broadcast and included.

Setting fees in practice

Max fee: set this high enough to accommodate a base fee spike. The base fee can only move 12.5% per block, so setting your max fee 2–3× the current base fee provides meaningful buffer without guaranteeing huge overpayment.
Priority fee: this is your tip to the validator. On most chains and under moderate congestion, 1–2 gwei is sufficient. During periods of high demand (NFT mints, protocol launches), priority fees can spike significantly.
Stuck transactions: if the base fee rises above your max fee, the transaction sits in the mempool until it falls back within range. Most wallets let you speed up by replacing the transaction with a higher max fee.