What Is RBF (Replace-by-Fee)?
Replace-by-Fee (RBF) is a Bitcoin protocol feature that allows an unconfirmed transaction to be replaced with a new version that pays a higher fee. This gives users flexibility to adjust fees if their transaction gets stuck in the mempool during periods of network congestion.
Key Aspects
Fee Bumping
RBF is primarily used to "bump" transaction fees when network conditions change. If you initially set a low fee and your transaction isn't confirming, RBF lets you increase it to compete for block space.
Zero-Confirmation Considerations
RBF transactions should not be accepted for zero-confirmation payments, as they can be replaced before being mined. Merchants should wait for confirmations when accepting RBF-enabled transactions.
Modern wallets increasingly support RBF by default, as it provides users with more control over transaction confirmation times. An alternative approach is CPFP (Child Pays for Parent), where the recipient can speed up confirmation.
Quick Facts
- •Defined in BIP125
- •Transaction must signal RBF opt-in
- •Sender can increase fees before confirmation
- •Alternative to CPFP