Fee Rate

Overview

In Bitcoin, a transaction pays the difference between total input value and total output value as its fee. Because transactions have different sizes, comparing only total fees would favor large transactions inefficiently. Fee rate normalizes the payment by the blockspace consumed.

Modern Bitcoin wallets commonly quote satoshis per virtual byte. Virtual size derives from transaction weight and discounts witness data according to SegWit rules. A transaction with more inputs, script data, or complex spending conditions generally has a larger virtual size and needs a larger total fee at the same rate.

Wallets estimate fee rates from recent blocks and mempool conditions for a target confirmation horizon. Estimates can be wrong when demand changes quickly. Nodes also enforce relay and replacement policies that can require a minimum incremental fee rate.

Payment and treasury systems should record the chosen fee rate, final virtual size, total fee, confirmation target, replacement setting, and change output. When a transaction is fee-bumped, replacement history should remain linked to the same intended payment and inputs.

Fee rate differs from Ethereum gas price. Both price resource consumption, but the resource units and transaction models are different. Users should not compare sat/vB directly with gwei per gas or infer confirmation security from a quoted rate.

In practice, a wallet can quote 20 sat/vB while the confirmed transaction has a different effective rate because its final weight or fee changed. Operations teams should store total fee, virtual size, quoted rate, and confirmed rate separately. This distinction matters when diagnosing delayed inclusion, comparing wallet estimates, or deciding whether a replacement transaction paid enough to compete.