Sending large amounts of Bitcoin is scary.
Especially when transactions get stuck.
“Did I just lose all my Bitcoin?”
It’s always a relief when your Bitcoin transaction goes from pending to confirmed.
If your transaction has been stuck on pending for a while, don’t stress.
Generally, it’s just a matter of waiting.
The network can become congested at times, which means that transactions can take a little longer than usual to be confirmed.
While you’re waiting, take the time to read this guide and refresh your memory on how Bitcoin transactions work, how to calculate the optimal fee, how long transactions usually take, and what you can do to speed up a transfer.
The process of sending a transaction is quite simple for the sender. All you have to do is:
Once submitted, your transaction generally isn’t processed immediately. It goes into the Mempool (short for memory pool), which is basically a waiting area for unconfirmed transactions. This site shows the current state of the Bitcoin Mempool.
The different colors represent different fee-levels. Blue is for transactions with 1-10 satoshis per byte, green for 10-40, and so on as per the legend on the left.
You’ll notice that there are zero red or purple colored transactions, which represent fee levels of over 250 satoshis/byte. As you might expect, the higher the fee, the quicker it will be processed.
Every transaction has to be checked and confirmed by the computers that maintain a full copy of the Bitcoin blockchain.
These are called nodes, and they are responsible for making sure that you actually own the bitcoin you’re sending. They do this by verifying your transaction against the history of the blockchain.
This is a computationally-intensive process, and one of the major features that gives the Bitcoin network its strength. Nodes - also called miners - are compensated for this work with the fees that every sender must pay to send a transaction.
Once the nodes are satisfied that your transaction is legitimate, it is accepted into a block and broadcast on the network. At this point, your transaction has one confirmation. As other nodes pick up the block and verify it, the number of confirmations will increase.
It’s up to you to decide how many confirmations you want when sending or receiving bitcoin, but generally:
To read more about confirmations, check out our guide here.
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An unconfirmed transaction is one that hasn’t yet been picked up by a miner and processed into a block. There are a number of reasons your transaction may be unconfirmed.
Each transaction takes the same amount of hash power to confirm, regardless of size. This can create a bottleneck at times of high congestion, where not even small transactions can sneak through.
Fluctuating network hash power can influence this, too. It’s a system supply and demand that is generally at an equilibrium. When a disequilibrium occurs, prices change to rebalance the network.
It’s easy for individual transactions to get caught up in network-wide occurences. For example, some recent research uncovered one reason for recurring spikes in network congestion and subsequent spikes in transaction fees. Bitcoin developer 0xB10C argued that BitMex was flooding the network with transactions at approximately 13:00 UTC every day.
This was an inadvertent effect of BitMex processing all withdrawals at the same time each day. They have since announced that they will begin batching transactions, which spreads them out across the day and reduces congestion.
The lower the fee, the less incentive miners have to verify your transaction. As you saw above in the snapshot of the Mempool, the bulk of pending transactions are green and blue, i.e. with a fee below 40 satoshis/byte. There is little incentive for miners to process these when they could be expending their hash power on more lucrative transactions.
A transfer or transaction ID (TXID) is a unique hash of the data of your transaction. It looks something like this:
You can send a TXID to the party receiving your BTC, so they know it’s on its way. They can then track the transaction’s progress on sites such as Blockchain.com, BlockCyper, or any other blockchain explorer tool.
This is what an unconfirmed transaction looks like. You can see that it is not included in any block, but is still in the Mempool. If we compare the fee paid for this transaction (122.636 satoshis/byte) to the status of the Mempool above, we can see that this is a pretty average fee, and so this particular transaction shouldn’t take too long to be processed.
If you have crypto on Coinbase that you want to withdraw to another wallet or sent to someone else, you may be wondering how long it takes. Luckily, you shouldn’t experience any of the delays associated with depositing funds to Coinbase.
It shouldn’t take any longer to send Bitcoin from Coinbase than to send it from any other wallet. Coinbase doesn’t give you the option to set the fee, instead it will default to a median value that will get your transaction processed as quickly and cheaply as possible.
If your transaction is stuck, you have a few options. The first - and the most boring - is to simply wait. Even with a very low fee, it is very likely that your transaction will eventually be processed. Generally, this shouldn’t take much longer than 24 hours, but if the network is exceptionally busy you could be waiting up to a couple of days for it to clear.
If you really want to get your transaction through as quickly as possible, two strategies you can use are:
The Replace By Fee method is the simplest and most reliable way of pushing through a stuck transaction. It involves rebroadcasting the unconfirmed transaction again, but this time with a higher fee. This works as long as the unconfirmed transaction really is unconfirmed, i.e. it has zero network confirmations.
This way, the double-spend problem is avoided. Many wallets such as Electrum allow you to replace a stuck transaction with one wth a higher fee.
The Child Pays For Parent method is a bit more technically advanced than Replace By Fee.
The idea is to create a new transaction (B) - the child - which uses part of the unconfirmed transaction (A) - the parent - as an input. This new transaction should have a relatively high fee attached to it. For miners to confirm Transaction B they will also have to include Transaction A into the block. If the fee of Transaction B is high enough to pay for both transactions, miners will prioritize it.
There is a useful guide here if you find yourself needing to push a transaction through using this method.
One benefit is that the recipient of a stuck transaction can push it through using the CPFP method, whereas RBF can only be done by the sender.
There are such things as transaction accelerators but it’s hard to recommend any of them. Transaction acceleration is basically a service offered by mining pools, where for a fee they will prioritize your transaction and put it at the top of their mining list. As the two methods outlined above work just fine, and transaction accelerators rely on trusted third parties, they should only be used as a last resort.
Of course, the easiest way to make sure that your transaction doesn’t get stuck in the Mempool is to use an appropriate fee the first time around. Fee calculators can help you find out what to set your transaction fee as.
We have a great fee calculator that uses up to the minute information to determine the optimal fee for your Bitcoin transaction.
Generally, you shouldn’t need to change the suggested value, unless you’re sending a transaction that either needs to be confirmed as soon as possible, or isn’t as urgent and can wait a few extra hours.
How long you bitcoin transaction is pending depends on the fee you set when you sent it. If you set low fees, you transaction may be pending for a very long time. If you set very high fees, you transaction may only be pending for 10 minutes.
A transaction confirms once it’s been included in a block. Each block is added approximately every 10 minutes (though can be more faster or slower than that). However, if you don’t set high enough fees, your transaction may not make it into the next block. Inclusion in a block is an auction of sorts. The transactions that make it into the next block are the ones who bid the highest.
Unlike transactions on the blockchain, bitcoin purchases on exchanges can be pending indefinitely. That is because it is up to the exchange to decide when they are going to accept your payment. The best thing to do with a bitcoin purchase stuck in a pending state is to reach out to the exchange you boguht the bitcoin on and ask them why.
While you technically cannot cancel a pending bitcoin transaction, you can effectively replace it with a replace-by-fee transaction or Child-Pays-for-Parent transaction. The difference between the two is that with RBF, you are rebroadcasting the same transaction while with CPFP you are creating a new transaction.