Thread by @AquaBitcoin

You thought #Bitcoin transactions were final once you hit send?

What if I told you… you can “edit” them? 👀

That’s what Replace-By-Fee (RBF) makes possible. 🧵👇🏻

💡 What is RBF?

Replace-By-Fee (RBF) is a #Bitcoin feature that allows the sender to replace an unconfirmed transaction in the mempool with a new version that pays a higher fee.

Until it’s confirmed in a block, a TX isn’t set in stone.

That means:

✅ You can update it
✅ You can bump the fee
✅ You can even redirect it

…as long as the new version follows the rules.

🚧 Problems RBF solves

✅ Stuck TXs → Low-fee TXs can linger in congestion.
✅ Time-sensitive TXs → Useful for Lightning channel opens/closures.
✅ Changed your mind? → Update recipients or amounts.
✅ Dynamic fees → Adjust to market conditions, no need to overpay upfront.

⚙️ How RBF works

Modern RBF was reintroduced in 2016 with BIP125, proposed by Peter Todd.

To replace a transaction, the new version must:

🔹Pay a higher absolute fee.
🔹Pay a higher fee rate (sats/vbyte).
🔹Avoid new double-spend risks.

github.com/bitcoin/bips/b…

In practice, it’s simple:

1️⃣ The sender creates a new version of the unconfirmed transaction.
2️⃣ The new version has the same inputs but pays a higher fee (and possibly different outputs).
3️⃣ The mempool replaces the old transaction with the new one.

🙌🏻 Benefits for users

🤝🏻 No more stuck transactions → If your fee is too low, just bump it and rebroadcast.

🫰🏻Flexibility → Edit the TX: send to another address or split, as long as you add a higher fee.

👍🏻 Control → Your TX stays “editable” until it confirms On-chain.

⚠️ What receivers must know

Because RBF lets the sender replace unconfirmed TXs, don’t treat them as final.

👉🏻 Merchants: Wait at least 1 confirmation before delivering goods/services.

👉🏻 P2P traders: Don’t release fiat until you see 1 confirmation.

🎯 Why RBF matters

Without RBF: a fee miscalculation = hours/days of waiting.

With RBF: just bump the fee → your TX gets confirmed.

👉🏻 Want to learn more about how #Bitcoin really works under the hood?

Follow us for deep dives on Bitcoin features like RBF, Lightning, and more. ⚡🐬