What is Replace-By-Fee (RBF)?

General Wallet Use

15 min

The Bitcoin network has faced a network congestion struggle for many years as more people use it. High transaction volumes are a good thing, but they can also lead to slower transaction confirmations. This also makes it frustrating for users who want their Bitcoin transactions to be sent and received quickly. 

Adding to the issues, new protocols and increasing adoption are driving up the number of transactions on-chain every day. With excitement about the growing ecosystem on Bitcoin, network traffic can become burdensome. Let’s explore how the Replace-By-Fee (RBF) feature can help manage congestion delays, even when the network is very busy.

What is Replace-By-Fee?

Replace-By-Fee (RBF) is a practical feature embedded in the Bitcoin network that allows users to pay for transaction priority. RBF makes it possible to replace an unconfirmed transaction with a new one that includes a higher transaction fee. This prevents transactions from getting stuck in the mempool—a place where unconfirmed transactions await inclusion in a block—because of insufficient funds.

When the Bitcoin network is congested, transactions with low fees can have longer confirmation times. Bitcoin miners, who are responsible for processing transactions, prioritize the ones with higher fees because they are more profitable. RBF addresses this challenge by enabling users to increase the fee of their transaction after it has been sent. This also increases its attractiveness to miners for faster confirmation.

How Does RBF Work?

When you initiate a Bitcoin transaction, it’s possible to set a low, standard, or high fee. The higher the fee, the faster your transaction will be confirmed. During low traffic times or when a transaction is not urgent, a low fee option may save on costs. But sometimes a user can misjudge traffic or find their transaction stuck.

If a transaction with a low fee remains unconfirmed in the mempool, RBF is an option to add fees and increase its likelihood of being confirmed. Using RBF, you can broadcast a new version of the same transaction but with a higher fee. This revised transaction retains the same inputs—mainly the source of the Bitcoin—but offers a higher fee to incentivize miners to prioritize it in the next block they mine. Once the new transaction is confirmed, the original unconfirmed transaction is automatically dropped from the mempool.

There are two primary types of RBF.

  • Full RBF allows a transaction to be replaced multiple times with progressively higher fees until it is confirmed.

  • Opt-In RBF requires the transaction to be initially marked as replaceable by setting a specific field (nSequence) to a value below a predefined threshold. This ensures only transactions explicitly marked for replacement can benefit from RBF..

Why Use RBF?

Replace-By-Fee (RBF) facilitates faster transaction confirmations by allowing users to increase the fee on a stuck transaction. This improves its chances of miners including it in the next block and provides flexibility in managing transactions. 

If a user initially sets a low fee or misjudges network conditions, RBF enables them to adjust and increase the fee accordingly. RBF also helps optimize transaction costs. Instead of waiting indefinitely for a low-fee transaction to confirm, users can proactively adjust the fee to achieve faster confirmation times.

However, RBF also introduces certain drawbacks:

  • One major concern is double-spending. Since RBF allows unconfirmed transactions to be replaced, there is a risk of inadvertently spending the same Bitcoin twice.

  • RBF can also complicate things for merchants and transaction recipients. It can make it difficult to determine which transaction is legitimate or final, potentially exposing recipients to fraud.

  • If many transactions utilize RBF in times of high network congestion, it may exacerbate overall congestion. This could lead to higher transaction fees and slower confirmation times for everyone.

  • There is potential for user error or accidental transaction replacements. This can cause delays or unexpected costs.

While RBF is a great feature with helpful transaction management properties, it’s not without risks. As with anything in crypto, make sure to understand how it works and carefully execute all transactions to avoid errors.

How Do You Use RBF?

Using Replace-By-Fee (RBF) is easy and straightforward with Bitcoin wallets like Leather, which provides a user-friendly interface to configure transaction fees and manage transactions effectively. 

A user-focused Bitcoin wallet that integrates the latest features and supports the most popular integrations will make your Bitcoin experience extremely versatile.

Here’s how to use RBF in a transaction using Leather wallet:

  • After sending a transaction, if it gets stuck due to a low fee, go to the “Activity” tab in your Leather wallet

  • Choose “Increase fee” on the transaction you want to modify

  • Set the increase amount and submit

Every wallet may have slightly different steps for using RBF. Follow the specific instructions provided by your wallet. This typically involves selecting the transaction you want to replace, choosing a higher fee, and confirming the changes.

Once you’re done, keep an eye on the status of your transaction in the wallet's activity or transaction history. Wallets like Leather will show the current fee rate, transaction ID, and status (pending, confirmed, etc.).

Make sure you’re always aware of the risks associated with RBF, such as the potential for double-spending and transaction errors. Use RBF judiciously, especially during times of high network activity.


Bitcoin has long held its position as the most secure and decentralized blockchain in the world. But it has not always been known as the fastest or cheapest blockchain for sending transactions. Tools and features like Replace-By-Fee and even emerging layer-2 solutions that help with network congestion and transaction speed are becoming more important.

As the Bitcoin ecosystem grows and more use cases become available, speed, efficiency, and cost effectiveness will remain a priority. Wallets like Leather, which provide all the best features in a user-friendly interface, make your Bitcoin experience better. And tools like RBF are steps forward on the path to solving long standing blockchain challenges.

Connect to web3 applications built on Bitcoin with the Leather browser extension. Install Leather – the only wallet you need to tap into the multilayered Bitcoin economy – today.

This article was updated on 7/1/24

This article was updated on 7/1/24