Transaction Fee

Definition

A transaction fee is the amount paid to have a transaction processed under a blockchain's rules and fee market. For an ordinary Bitcoin transaction, it equals the total value of the inputs minus the total value assigned to outputs. Miners may claim those fees when the transaction is included in a valid block. Wallets commonly estimate an appropriate fee using transaction virtual size and a rate quoted in satoshis per virtual byte. The amount of BTC being transferred is not itself the main measure of required block space: input count, output structure, and spending conditions are important. A higher fee can improve a transaction's competitiveness but cannot promise an exact confirmation time. An exchange's withdrawal charge is also not necessarily identical to the on-chain fee it pays. Other blockchains use different mechanisms, including gas accounting, so fee terminology should be interpreted in network context.