CPFP calculator (Child Pays for Parent)

Calculate the fee a new “child” transaction must pay so miners confirm it together with your stuck “parent” transaction.

Stuck parent TXID (auto-fill)

Parent size (vB)

Parent fee paid (sats)

Child transaction type

Child size (vB)

Target fee rate (sat/vB) — next block by default

How CPFP works

Miners evaluate a transaction together with its unconfirmed ancestors as a “package”. If you control one of the outputs of a stuck transaction (for example, you are the receiver, or it has change coming back to you), you can spend that output in a new child transaction with a high fee. To collect the child's fee, a miner must also include the parent — so both confirm together.

The formula is simple: child fee = target rate × (parent vB + child vB) − parent fee. This calculator does it for you using the live next-block rate.

When CPFP is not possible

You need an unspent output of the parent in a wallet you control, and your wallet must let you choose that specific coin (coin control) or offer a “bump fee/CPFP” button. If you sent coins to someone else with no change, or your wallet can't do it, use premium acceleration instead. Read the full CPFP guide.