Replace By Fee (RBF)
bitcoin · policy · fees
A mempool policy that can accept a conflicting unconfirmed transaction when the replacement satisfies fee and relay rules.
Replace By Fee (RBF) lets a node replace an unconfirmed mempool transaction with a conflicting version under defined policy rules. Wallets commonly use it to raise the fee of a delayed payment.
BIP125 described opt-in signaling through transaction sequence numbers. Full-RBF policy evaluates replacements even when the original did not signal. Bitcoin Core changed its defaults over time, so "RBF" should not be treated as one permanent network-wide rule.
RBF is a fee-management tool and a reminder that mempool acceptance is not settlement. A receiver delivering irreversible value before confirmation should assess conflicts, transaction value, network policy, and available double-spend detection.
Related terms
Opt-in RBF
→BIP125 signaling that marks an unconfirmed Bitcoin transaction as replaceable under opt-in relay policy.
policy · mempool · fees
Mempool
→A node's local set of unconfirmed transactions accepted for possible relay and block inclusion.
blockchain · node
Fee Rate
→Transaction fee per unit of size: commonly sat/vB for Bitcoin or sat/byte for Bitcoin Cash. It helps explain miner selection, not a guaranteed wait.
blockchain · economics
Double Spend
→A double spend is an attempt to spend the same coins twice by getting one conflicting transaction accepted over another.
scam · security · blockchain · technical
Zero Confirmation
→A transaction observed before any block has included it.
transaction · security