CPFP (Child Pays For Parent) – Fee Bumping Made Simple

When working with CPFP, a fee‑bumping technique where a new transaction pays enough fee to pull an older unconfirmed transaction into a block. Also known as Child Pays For Parent, it lets users accelerate stuck payments.

The method hinges on the child transaction, the newer transaction that includes a higher fee paying for the parent transaction, the original low‑fee transaction waiting in the mempool. By bundling them, miners see a single package that meets the fee threshold, so both confirm together. CPFP therefore encompasses fee bumping, requires a child transaction, and influences miner selection. It works even when the parent transaction is not RBF‑enabled, making it a reliable fallback for users who missed the optimal fee window.

When to Use CPFP vs. Other Fee Strategies

Fee bumping can be tackled in three main ways: CPFP, Replace‑by‑Fee (RBF), and the newer EIP‑1559, a protocol upgrade that separates base fee and tip to improve fee predictability. CPFP shines when a transaction is already in the mempool and cannot be replaced, or when you need an instant confirmation for a time‑sensitive payment. RBF, on the other hand, lets you resend the same transaction with a higher fee, but it requires the original to be flagged as replaceable. EIP‑1559 adds a tip (priority fee) that miners prioritize, yet it still leaves low‑fee transactions vulnerable to delay.

Practical tips for using CPFP: first, calculate the combined fee needed to meet the current mempool median; second, ensure the child transaction includes a sufficient tip to make the package attractive; third, monitor the mempool size with a block explorer or a fee‑estimator tool. Many wallets now automate CPFP by suggesting a child transaction when a parent stalls. Remember, the goal is to create a fee‑rich bundle that satisfies the miner’s profit motive, so both transactions confirm in the next block.

Below you’ll find a curated list of articles that dive deeper into CPFP mechanics, compare it with RBF and EIP‑1559, and show real‑world examples of how traders and developers use this technique to keep their crypto moves flowing smoothly.