Child Pays for Parent (CPFP): A Solution to Speed Up Bitcoin Transactions

Andika

08 Feb 2025 — 3 min read

In the Bitcoin network, transactions with low fees often get stuck in the mempool and are not immediately processed by miners. One solution to this issue is the Child Pays for Parent (CPFP) technique. This method allows a new transaction with a higher fee to help speed up the confirmation of an older, lower-fee transaction.

What is Child Pays for Parent (CPFP)?

Child Pays for Parent (CPFP) is a strategy in Bitcoin where the recipient of a transaction can create a new transaction (child transaction) with a higher fee to incentivize miners to confirm the older (parent transaction), which has been delayed due to a low fee.

This technique takes advantage of how miners operate—always prioritizing transactions with the highest fees to maximize their earnings. By offering a child transaction with a high fee, miners are encouraged to first process the parent transaction so that the child transaction can be included in the next block.

How Does CPFP Work?

1. Parent Transaction Gets Stuck

Alice sends Bitcoin to Bob with a very low transaction fee.
Due to the low fee, the transaction remains in the mempool and is not confirmed by miners.

2. Recipient Creates a Child Transaction

Bob, who received Bitcoin from Alice, wants to use the funds immediately.
Bob then creates a new transaction (child transaction), where he sends a portion of the Bitcoin to another address with a significantly higher fee.

3. Miners Process Both Transactions

Since the child transaction depends on the parent transaction, miners cannot confirm the child transaction without first confirming the parent transaction.
Because the child transaction has a higher fee, miners are incentivized to process both transactions to maximize their rewards.
As a result, Alice’s previously stuck transaction is also confirmed.

When is CPFP Used?

CPFP is particularly useful in the following scenarios:

Low-Fee Transactions Stuck in Mempool
If the sender (Alice) sets a transaction fee too low and does not enable Replace-By-Fee (RBF), the recipient (Bob) can speed up the process using CPFP.
Wallets That Do Not Support RBF
Some wallets do not provide an option to increase transaction fees after sending. In such cases, CPFP is the only solution available to the recipient.
Urgent Transactions
If the recipient needs to use the received Bitcoin immediately, but the transaction is still stuck in the mempool, CPFP can help speed up confirmation.

Advantages and Limitations of CPFP

Advantages of CPFP

✅ Speeds Up Stuck Transactions – A useful solution for transactions delayed in the mempool.
✅ Can Be Used by the Recipient – Unlike RBF, which must be enabled by the sender, CPFP allows the recipient to take action.
✅ Leverages Miner Incentives – Miners are motivated to process transactions that offer higher fees.

Limitations of CPFP

❌ Not All Wallets Support CPFP – Some wallets do not provide an option to create a child transaction.
❌ Higher Costs – Since it requires creating a new transaction with a higher fee, the total cost may be greater.
❌ Only the Recipient Can Use It – The sender cannot initiate CPFP, so if the recipient does not act, the transaction may remain stuck.

Conclusion

Child Pays for Parent (CPFP) is a technique that allows Bitcoin recipients to speed up stuck transactions by creating a new transaction with a higher fee. By leveraging the incentive system within the Bitcoin network, miners are encouraged to prioritize transactions that provide better rewards.

While CPFP is an effective solution in many cases, Bitcoin users should always be aware of transaction fee structures and wallet features to prevent stuck transactions in the first place.

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