Child Pays For Parent (CPFP): Definition and How Bitcoin Speeds Up Stuck Transactions
Child Pays For Parent (CPFP) is a Bitcoin fee management technique that accelerates the confirmation of an unconfirmed transaction by creating a child transaction with a sufficiently high fee. Because miners typically evaluate the combined profitability of related transactions, they are incentivized to include both the parent and child transactions in the same block.
Child Pays For Parent (CPFP) Explained in Simple Terms
Sometimes a Bitcoin transaction becomes stuck because its fee rate is too low.
Since Bitcoin transactions can only spend confirmed or unconfirmed outputs that belong to them, a second transaction can be created using one of the outputs from the original transaction.
This second transaction is called the child transaction.
If the child pays a high enough fee, miners may decide that confirming both transactions together is more profitable than ignoring them.
As a result, the low-fee parent transaction is confirmed along with the high-fee child transaction.
Unlike Replace-by-Fee (RBF), CPFP does not replace the original transaction. Instead, it builds on top of it.
How Child Pays For Parent (CPFP) Works
CPFP uses the dependency between related Bitcoin transactions.
The process works as follows:
Parent Transaction Broadcast
A Bitcoin transaction is sent with a low fee.Transaction Remains Unconfirmed
It stays in the mempool because miners prioritize higher-fee transactions.Child Transaction Created
The recipient or sender spends one of the parent transaction's outputs.High Fee Attached
The child transaction pays a significantly higher fee rate.Miners Confirm Both Transactions
Because the child cannot be confirmed without the parent, miners typically include both in the same block.
The concept can be summarized as:
Low-Fee Parent + High-Fee Child → Higher Combined Fee → Faster Confirmation
Example of Child Pays For Parent (CPFP) in Practice
Alice sends 0.5 BTC to Bob.
The transaction pays only 5 sat/vB, and it remains unconfirmed during a period of heavy network congestion.
Bob urgently needs access to the funds.
Instead of waiting, Bob creates a new transaction that spends the unconfirmed Bitcoin he is about to receive and attaches a fee rate of 80 sat/vB.
Because miners evaluate the total fee earned from both transactions, they are motivated to confirm:
Alice's original transaction
Bob's child transaction
Both transactions are included in the same block.
Why CPFP Matters
CPFP provides a practical solution for transactions that would otherwise remain stuck in the mempool.
It offers several benefits:
speeds up confirmation
helps recipients influence confirmation time
works even when the sender cannot modify the original transaction
improves flexibility during network congestion
reduces the need to wait for mempool activity to decrease
It is one of Bitcoin's most useful fee management mechanisms.
CPFP vs Replace-by-Fee (RBF)
Child Pays For Parent (CPFP)
Works by:
creating a new child transaction
Typically used by:
the recipient
the sender (if they control a spendable output)
Original transaction:
remains unchanged
Replace-by-Fee (RBF)
Works by:
replacing the original transaction with a higher-fee version
Typically used by:
the sender
Original transaction:
is replaced before confirmation
Both methods improve confirmation speed, but they operate in fundamentally different ways.
Why Miners Accept CPFP Transactions
Miners maximize their revenue by selecting the most profitable transactions.
When evaluating CPFP transactions, miners often consider the combined fee rate of the entire transaction package rather than each transaction individually.
For example:
Parent fee: 1,000 satoshis
Child fee: 9,000 satoshis
Combined:
Total fee: 10,000 satoshis
If the package provides a competitive overall fee rate, confirming both transactions becomes economically attractive.
CPFP and the Mempool
Both the parent and child transactions remain in the mempool until they are mined.
Because the child depends on the parent:
the child cannot be confirmed first
both transactions are confirmed together
if the parent disappears from the mempool, the child becomes invalid
This dependency is a fundamental part of how CPFP works.
Do All Wallets Support CPFP?
Not necessarily.
Many modern Bitcoin wallets automatically support CPFP or provide manual options for creating child transactions.
However, implementation varies between wallets.
Advanced wallets typically provide greater control over:
UTXO selection
transaction construction
fee management
When Should CPFP Be Used?
CPFP is particularly useful when:
the original transaction has a very low fee
the recipient needs confirmation quickly
Replace-by-Fee is unavailable
network congestion is unusually high
In these situations, CPFP can often accelerate confirmation without modifying the original transaction.