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.

EIP-1559 Transaction Fee Calculator

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.

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, so dividing the gas-times-price product by 10 to the power of 9 converts to ETH. The min() is the heart of EIP-1559: you can set a generous max fee for safety without overpaying when the network is calm.

Example and tips

With a base fee of 25 gwei, a max priority fee of 2 gwei, a max fee of 40 gwei, and a 21,000 gas transfer, the effective price is 27 gwei (25 + 2, which is below the 40 cap). Of that, 25 gwei per gas is burned and 2 gwei per gas tips the validator, for a total of 0.000567 ETH; the headroom up to 40 gwei is simply not spent. Set your max fee a few multiples above the current base fee so a sudden fee spike does not strand your transaction, but keep your priority fee modest — one or two gwei is usually enough outside congestion.