Replace-by-fee (RBF)
Replace-by-fee (RBF) lets you replace a waiting Bitcoin transaction with a new version of it that spends the same coins and pays a higher fee.
A new version of a waiting transaction that spends the same coins with a higher fee, so it takes the old one's place in the mempool. Most wallets call it "speed up" or "bump fee". It is not a second payment: once either version is in a block, the other can never go through.
How do I use RBF?
In most wallets it is the "speed up" or "bump fee" button on a waiting transaction. The wallet signs a new version with a higher fee rate. It must pay more in total than the original, and the original then drops out of mempools.
Does the original have to allow it?
It used to: BIP 125 had wallets mark a transaction as replaceable. Most nodes now accept a better-paying replacement either way, the default in Bitcoin Core since version 28, so a merchant should never treat an unconfirmed payment as final.
Sources
Updated 10 Oct 2026
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