You can use transaction accelerators or CPFP to increase your fee rate.
Bitcoin transactions cannot be canceled. When you broadcast a transaction to the bitcoin network, it must be mined into a block on the blockchain to become confirmed. Until it’s confirmed, it will wait with other unconfirmed transactions in the mempool. Miners prioritize the transactions with the highest fee rate (sats/vb). As the global demand to move bitcoin fluctuates, so do fee rates.
If you broadcast a transaction with a low fee rate, your transaction can get stuck waiting for confirmation, possibly for hours, days, weeks, or even longer. If necessary, you can pay more to increase the prioritization of your transaction confirmation.
How to check if it makes sense to accelerate your transaction
- Sign in to your Unchained account at my.unchained.com.
- Navigate to your vault by clicking Vaults. Select the name of your vault that has a broadcasted withdrawal transaction.
- In the Transact box, select View Transaction.
- Click on the magnifying glass symbol to the right of your Transaction ID. This will open a new tab and show your transaction in mempool.space.
- Look for the section that says ETA. If it says “not any time soon” you may want to take steps to accelerate your transaction. You can also compare your transaction’s fee rate (in sats/vb) to the high priority fee rate shown on the mempool.space home page.
Method 1: Paying miners out-of-band
You can use a service such as Mempool Accelerator or ViaBTC transaction accelerator to pay additional fees directly to miners, who will accelerate your transaction.
Caution: Unchained is not affiliated with external transaction accelerator services, and we do not provide direct support for these services. Before you decide to use a service like this, please do your own research and proceed at your own risk.
For example, here are some steps if you decide to explore the Mempool Accelerator option:
- Sign in to your Unchained account at my.unchained.com.
- Navigate to your vault by clicking Vaults. Select the name of your vault that has a pending withdrawal transaction.
- In the Transact box, select View Transaction.
- Click on the magnifying glass symbol to the right of your Transaction ID. This will open a new tab and show your transaction in mempool.space.
- Look for the Mempool Accelerator section. Here, you will see the estimated cost and expected confirmation speed. You can select Accelerate to view payment options if you wish to proceed.
Method 2: Child Pays for Parent (CPFP)
For some withdrawal transactions, you can use child pays for parent, or CPFP. You can only utilize this method if your transaction includes change coming back to you. This is the most common situation unless you send your full vault balance at once. The goal of CPFP is to conduct another transaction that will spend the change from your original transaction with a higher fee rate.
Warning: Performing a CPFP is a technical operation requiring both of your keys (the Unchained backup key is not a good choice for time-sensitive transactions). Additionally, if the transaction doesn’t include change coming back to you, CPFP may not be able to be used.
You can purchase a Premium Support session if you'd like to speak one-on-one with a bitcoin expert to walk through the CPFP process. Please note that Premium Support call availability is sometimes constrained. If your transaction is urgent, consider a different acceleration method.
To attempt a CPFP on your own, follow these steps:
Find the appropriate fee rate for your CPFP transaction.
- Sign in to your Unchained account at my.unchained.com.
- Navigate to your vault by clicking Vaults. Select the name of your vault that has a pending withdrawal transaction.
- In the Transact box, select View Transaction.
- You will see your Transaction ID. Copy it.
- CPFP Calculator is an open source tool that can help calculate the appropriate fee rate for your CPFP transaction. Paste your Transaction ID here.
- Choose "P2SH (legacy multisig)" for the input and output types.
- Submit the information and note the resulting CPFP Fee Rate, written in red.
Import your vault into Caravan.
- Load your vault into Caravan to perform the CPFP.
- Once you load your vault into Caravan, hit Send. Turn the Manual switch on to select which address you are spending funds out of.
- Look for the address that says Pending in the Last Used column. This should be the address poised to receive your change from your original transaction. This is the address to spend funds out of, so check the box on the left side.
- In the Address field, you can paste a deposit address from your vault or click the gray wallet icon on the right side, which will automatically apply one of your vault addresses.
- Enter the CPFP Fee Rate number you noted earlier into the Fee Rate field on Caravan.
Complete and broadcast the transaction.
- Once you’ve entered your fee rate, select the gray circle in the far right containing a plus sign. This amount of bitcoin will be sent back to your vault.
- Select Preview Transaction, and follow the normal withdrawal steps to sign and broadcast the CPFP transaction.
- You’re done! Both the CPFP transaction and the original transaction will now have an effective fee rate that approximately matches the recommended high fee rate, so they are confirmed sooner.