Which situation are you in?
You are the receiver
Someone paid you, and it is stuck with a low fee. You cannot change their transaction, but the output that pays you is yours. Spend it with child-pays-for-parent: a new “child” transaction sending that output to another address of yours, with a fee high enough that miners take the parent and child together. The builder above works out the fee, checks it is safe, and gives you an unsigned PSBT to sign in a wallet that controls the output.
An exchange withdrawal is stuck
Contact the exchange first — they control the sending wallet and can often bump the fee themselves. The output paying you is yours, so you can also CPFP it from your receiving wallet.
Your wallet is simple or custodial and has no bump button
Usually the best choice is to wait: demand falls at night and at weekends. If the output sits in a wallet whose keys you control, you can import the seed into a wallet like Sparrow or Electrum and use CPFP there. As a last resort, a paid service like the mempool.space Accelerator asks participating miners to prioritise it — it is paid, out-of-band and not guaranteed.
You sent it
If you sent it from a wallet with a “Bump fee” or “Speed up” button, use that — it replaces the transaction with a higher-fee version (Replace-by-Fee). The status check shows a target fee.
How the CPFP math works
Miners look at the package fee rate: the total fee of the stuck transaction, any unconfirmed transactions it depends on, and your child, divided by their total size. To reach a target rate, the child must pay target × (package size + child size) − fees already paid. The builder reads unconfirmed ancestors from mempool.space and includes them, because they must be mined too. It also makes sure the child pays at least the target rate on its own and at least the minimum relay fee.
The child has exactly one input (your output) and one output (your destination) — no change. Its size depends on the type of your output: native SegWit and Taproot are cheapest, legacy is most expensive. For multisig and other scripts, the size cannot be known in advance, so the builder refuses rather than guess.
Safety checks
- If the fee would be larger than your output, or leave less than the dust limit, the builder refuses.
- If the fee is more than 20% of your output, it warns you; above 50%, it warns loudly. Waiting may be better.
- If the stuck transaction already pays the target, it tells you a child is unnecessary.
- If information about related unconfirmed transactions can’t be loaded from mempool.space, it refuses to build a PSBT rather than guess the fee — just retry a minute later.
A note on Binance’s accelerator
Binance’s Transaction Accelerator is being discontinued as part of the closure of Binance Pool on 10 November 2026 (07:00 UTC), according to Binance’s announcement (reported by CoinMarketCap). CPFP and RBF do not depend on any accelerator.
Worked example
You received 50,000 sats to a bc1q address in a 141 vB transaction that paid only 282 sats (2 sat/vB); the market wants 15 sat/vB. A SegWit-to-SegWit child is about 110 vB, so the package must pay 15 × (141 + 110) = 3,765 sats. The parent paid 282, so the child pays 3,483 sats (≈ 31.7 sat/vB on its own), sending 46,517 sats to your fresh address. That is 7% of the output — no warning. Import the PSBT in Sparrow, check the one input and one output, sign, broadcast.
Frequently asked questions
Can I practise on Signet or Testnet4?
Yes. Switch the network selector to Signet or Testnet4. Status checks then use mempool.space’s test-network explorer, destinations must be test-network addresses (tb1…, m…, n… or 2…), and the CPFP builder makes a test-network PSBT. Test coins have no value, so it is a safe way to try CPFP before you need it. This site still never broadcasts.
My payment is stuck and my wallet has no “bump fee” button. What can I do?
If the stuck transaction pays you, you can use child-pays-for-parent (CPFP): spend your incoming output in a new transaction with a higher fee, so miners take both together. This page builds that transaction as an unsigned PSBT that you sign in a wallet that controls the output.
What is Child-Pays-for-Parent (CPFP)?
Miners judge related unconfirmed transactions as a package. If a child spends an output of a stuck parent and pays a high fee, the average fee rate of the package rises, and miners include both. The receiver can do this with their incoming payment, and the sender with their change.
Is a PSBT safe to paste into this site’s output?
A PSBT (Partially Signed Bitcoin Transaction) is an unsigned transaction proposal. It contains no keys and cannot move funds until you sign it in your own wallet. This site never asks for keys, seeds or xpubs, and never broadcasts anything.
Will my hardware wallet sign it?
Often, via its desktop companion. Hardware wallets need key-derivation (BIP-32) details that this site cannot know. Wallets like Sparrow and Electrum usually recognise their own output and add those details when you import the PSBT. If yours cannot, use its built-in CPFP feature instead.
My withdrawal from an exchange is stuck. What should I do?
Contact the exchange first: they control the sending wallet and can often bump the fee. The output that pays you is yours, though, so you can also CPFP it from your receiving wallet with the builder on this page.
Should I use a transaction accelerator?
Only as a last resort. Services like the mempool.space Accelerator are paid, work out-of-band with participating miners and are not guaranteed. Never send coins to someone who contacts you offering to speed up a transaction. Binance’s Transaction Accelerator is being discontinued together with Binance Pool on 10 November 2026; RBF and CPFP do not depend on any such service.
Is my bitcoin lost if the transaction is stuck?
No. An unconfirmed transaction either confirms eventually or is dropped, in which case the coins remain spendable by the sender. Nobody can take them while it is pending.
Why does “not found” not mean failed?
Bitcoin has no failure receipt. An ID that is not on mainnet right now may have a typo, belong to another network, have been replaced by a fee bump, have been dropped, or not have propagated yet. This tool never claims certainty.
How many confirmations do I need?
One confirmation already makes reversal very unlikely for everyday amounts. Many services wait for 3 to 6 for larger payments.
Why did the builder refuse to make a PSBT?
Besides unsafe amounts (fee larger than the output, dust, or an unknown script type), it refuses whenever it cannot load the stuck transaction’s unconfirmed ancestors from mempool.space. Without them the fee could be too low and your payment would stay stuck. Wait a minute and press Retry.
Does auto-refresh notify me?
No. It only updates this page every 30 seconds while it is open and visible. No notifications, no backend.