What Are the Fee-Bumping Rules (E.g. Minimum Fee Increase) for a BIP125 RBF Replacement?

BIP125, the Opt-in RBF standard, specifies two primary fee-bumping rules for a replacement transaction. First, the replacement transaction's total absolute fee must be greater than the original transaction's fee plus the fee required to cover the new transaction's size.

Second, the replacement must pay a higher fee rate (sat/vbyte) than the original. This ensures the replacement is always more economically attractive to miners and prevents spamming the network with marginally higher-fee transactions.

How Does a High Volume of RBF Transactions Affect the Overall Size of the Mempool?
How Does the Concept of “Double-Spending” Differ from RBF?
What Is the Practical Difference between “Opt-in RBF” and “Full RBF”?
Is a Higher Option Premium Always Correlated with a Higher Minimum RFQ Size?
Does RBF Allow a User to Change the Recipient of a Transaction?
What Is the Significance of the ‘Nsequence’ Field in Enabling RBF?
How Do Exchanges Typically Manage the Risk of RBF-enabled Deposits?
How Is the Holding Period of the Replacement Security Adjusted after a Wash Sale?

Glossar