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The London hard fork introduced EIP-1559 to Polygon, modifying how gas estimation and transaction costs work.

What changed

Before EIP-1559, transactions specified a single gasPrice field. Miners prioritized transactions with higher gasPrice bids. This model made gas estimation unpredictable during periods of high demand. EIP-1559 introduced a new transaction type, Type 2, which splits the old gasPrice into two components:
  • baseFee: a network-determined fee that is burned, calculated based on how full the previous block was. All transactions must pay this fee.
  • priorityFee (tip): an optional amount offered to the validator to prioritize the transaction.
The relationship is: maxFeePerGas sets the ceiling on what you are willing to pay. The actual fee paid is baseFee + priorityFee, where priorityFee = min(maxPriorityFeePerGas, maxFeePerGas - baseFee). Legacy Type 0 transactions remain compatible but the Type 2 format is recommended.

Legacy transaction (Type 0)

In a legacy transaction, only gasPrice is specified:

Type 2 transaction (EIP-1559)

Type 2 transactions use maxPriorityFeePerGas instead of gasPrice. The baseFee is paid regardless, so only the tip is bid:

Gas estimation

The Polygon Gas Station V2 provides current gas fee estimates:
Sample response:

See also