Child Pays for Parent

[RapTarX]

Doesn't the topic title sound cool?

CPFP- Child Pays for Parent

Imagine, you are selling your artworks through online and accepting bitcoin as payment. You have sold an artwork and received payment with bitcoin. Since the buyer has paid a lower fee, the transaction is stuck on the blockchain, no confirmation yet. What can you do? Ask buyer to send the transaction again with higher fee (RBF)? You may not ask him, or you may not get contacted with him if you need the BTC urgently.

Here's CPFP method to help you out.

When buyer have sent the BTC, your balance is updated with the amount with unconfirmed.
Since you need to send someone or you want to hold the BTC on your another address or since unconfirmed tx is not good, you can follow this method.
Send an amount of BTC (including the unconfirmed input) to another of your address using the maximum fee for being included at the next block. You can get the fee here- https://bitcoinfees.info/
You have paid highest required fee, miners will now give your transaction more priority than others. When they will check, validate and confirm your transaction, they will forcefully include the previous unconfirmed tx from your buyer as well.

So, what's the child and parent things here? When you send BTC, there will always be two terms, one is input(where BTC comes from) and output (where it is heading to). From input, you are creating an output. Input is the parent of the output  

Hope it was so easy for you to understand. Don't hesitate to ask a question.

If my explanation was wrong, I request the senior member to correct me. I'm a learner here, not for a long time.

Correction

the biggest problem you will face for using CPFP is when the wallet software that you are using doesn't have the feature to allow you to spend unconfirmed transactions. if it doesn't then you will have to use CPFP with unconventional ways such as creating the transaction yourself and signing through console,....
and usually if the wallet has that option it also has the CPFP option too in which case you should trust that it takes care of fee calculation and suggests the appropriate one (no need to use a website to guess the fees that are in most cases doing a very poor job).

[1714897401]

1714897401

[Deathwing]

Quick input, you may want to change the URL for Bitcoinfees. Omit the www part like https://bitcoinfees.info this. The site doesn't work otherwise.

Also, the explanation isn't really "in layman's terms" per se. CPFP is where you tell miners to mine your latest transaction that you created with the unconfirmed transaction by giving them a higher fee, this, in return confirms your unconfirmed transaction.

Thanks for the write-up.

[pooya87]

the biggest problem you will face for using CPFP is when the wallet software that you are using doesn't have the feature to allow you to spend unconfirmed transactions. if it doesn't then you will have to use CPFP with unconventional ways such as creating the transaction yourself and signing through console,....
and usually if the wallet has that option it also has the CPFP option too in which case you should trust that it takes care of fee calculation and suggests the appropriate one (no need to use a website to guess the fees that are in most cases doing a very poor job).

[Lafu]

There is also a Service called " https://bitaccelerate.com/ " where it is possible to boost transactions !

Free Bitcoin Transaction Accelerator

BitAccelerate is a free Bitcoin transaction accelerator that allows you to get faster confirmations on your unconfirmed transactions.
Just enter the transaction ID (TXID) and click the "Accelerate" button.
Our service will rebroadcast the transaction via 10 Bitcoin nodes.

When more people start to use Bitcoin, the block size reaches the limit and leads to crowded Bitcoin network.
As a result, some transactions are delayed, waiting for confirmation.
To speed up the process, these Bitcoin users have to pay higher miner fees and/or use SegWit transactions.

Source : https://bitaccelerate.com/

And also maybe an helpful page is https://bitcoinfees.net/

Confirmation time:  ≤ 20 min.  |  ≤ 1 hour  |  ≤ 6 hours  |  ≤ 24 hours  |  ≤ infinity

Average transaction fee: $0.28 (1 input, 2 outputs, SegWit, 1 hour conf. time.)

Source : https://bitcoinfees.net/


I never used the Service and just read about so if you use it , its at your one risk to do !
Hope this helps also and thanks for the thread.

[o_e_l_e_o]

Our service will rebroadcast the transaction via 10 Bitcoin nodes.

Rebroadcasting will only "speed up" your transaction if it is has been dropped from the mempool; it won't change your transaction's position in the mempool, which is entirely dependent on the fee you have paid. This service is useless unless your transaction has been dropped by a number of nodes, which will generally only happen if you've paid a very small fee and the mempool has been particularly full, in which case it will either drop off the bottom due to the mempool size limit, or it will timeout.

And also maybe an helpful page is https://bitcoinfees.net/

Looking at the number of transactions at each fee is less helpful than looking at the size of all the transactions at that fee. 100 transactions could take up less space in a block than 1 transaction. I would always advocate for using the third graph on this site - https://jochen-hoenicke.de/queue/#0,8h "Mempool Size in MB" - to see how far from the tip of the mempool your fee would be.

[Lafu]

As i have written i dont have used the service they offer and dont know how exactly they are working .
Was thinking maybe it brings some help for about slow transactions .
Have read about that a long time ago and remember about it as i have read the thread .

[Rmcdermott927]

I’ve done CPFP transactions on my own and it has saved me big time.  I remember using but pay for something during a period of high volume and the fee was too low.  I sent another Tx from the same address with a ridiculously high fee and it confirmed in the next few blocks. 

[Casdinyard]

Would the fee will change when the mempool is congested? Or will be the same as this.


Or could I still adjust the highest fee as possible? However, that will contradict on the 10 minutes confirmation because of 1mb capacity of mempool. Does it?

[RapTarX]

Would the fee will change when the mempool is congested? Or will be the same as this.


Or could I still adjust the highest fee as possible? However, that will contradict on the 10 minutes confirmation because of 1mb capacity of mempool. Does it?

Which wallet are you using? I don't know if bitcoin core suggest the required network fee, but in Electrum you can get the recommended fee. If you follow Electrum recommendations, and pay the highest recommended fee, your transaction must be included in the next block which is within 10 minutes.
You also can pay high fee than recommendations, in fact, you can pay as much as you want although that's unnecessary.

[o_e_l_e_o]

Would the fee will change when the mempool is congested? Or will be the same as this.

Those numbers will change as the mempool fills/empties. They are poor numbers to go on, though. They use dollars per transaction and assume an average transaction size, and both the current price of bitcoin and the size of your transaction could vary quite a lot, meaning paying that fee might be far too small for a fast confirmation.

Or could I still adjust the highest fee as possible? However, that will contradict on the 10 minutes confirmation because of 1mb capacity of mempool. Does it?

You can pay any fee you want. You could pay a fee of an entire bitcoin if you wanted. It would be completely unnecessary, though, as it can't confirm any faster than in the next block, so you will still be waiting 10 minutes on average. As I said above, if you absolutely must get in to the next block, but still want to pay the smallest possible fee, then go to the third graph here - https://jochen-hoenicke.de/queue/#0,8h "Mempool Size in MB" - mouse over the far right, and pick a fee (in sat/byte) that will put you very close to the tip of the mempool, probably less than 0.1 MB, but maybe even closer if the the mempool is rapidly filling up.

[Casdinyard]

Would the fee will change when the mempool is congested? Or will be the same as this.

Those numbers will change as the mempool fills/empties. They are poor numbers to go on, though. They use dollars per transaction and assume an average transaction size, and both the current price of bitcoin and the size of your transaction could vary quite a lot, meaning paying that fee might be far too small for a fast confirmation.

Great. That makes sense now as I am wondering why that fee is way too small even the transaction could possibly on the next block.

Which wallet are you using? I don't know if bitcoin core suggest the required network fee, but in Electrum you can get the recommended fee. If you follow Electrum recommendations, and pay the highest recommended fee, your transaction must be included in the next block which is within 10 minutes.
You also can pay high fee than recommendations, in fact, you can pay as much as you want although that's unnecessary.

Yup, I actually tried once to lower the fee and it completed the confirmation in about 24 hours though it's fine as I was really expecting it and not in a hurry.

[pooya87]

fee in bitcoin is the money you pay to "buy" a portion of a finite commodity called "block space". and in that purchase you are competing with others. if there aren't others outbidding you, you can pay the lowest and if there are others outbidding you, you have to pay higher.
so when there is a big backlog (bigger mempool) paying higher fees you have to pay higher than them to get a high priority.
and when it comes to CPFP you are buying space for 2 transactions instead of one so you have to keep that in mind when calculating the fee for the second (child) transaction.

[Olaphash]

Using a wallet that supports Segwit is the best option to avoid slow transaction confirmation.

If my explanation was wrong, I request the senior member to correct me. I'm a learner here, not for a long time.

Your topic and post is absolutely informative and I enjoyed it. But point of correction, you don't have to wait for a senior member to correct you as there are also some forum members below your rank with more explanatory answers to what you may not understand.

[o_e_l_e_o]

Using a wallet that supports Segwit is the best option to avoid slow transaction confirmation.

Simply using a SegWit address doesn't mean your transaction will necessarily confirm any faster. Considering a transaction with Legacy inputs and a transaction with SegWit inputs, if they both have the same fee rate in terms of sats/vbyte, then they will both have the same priority in the mempool and will both take equally long to confirm.

What using SegWit addresses does is make any resulting transaction smaller in terms of bytes, so the same fee rate in sats/vbyte works out as a smaller overall fee in sats. If you were to pay the same overall fee in sats as an identical transaction from a Legacy address, then your fee rate (sats/vbyte) would be higher, and therefore lead to a faster confirmation.

[RapTarX]

you don't have to wait for a senior member to correct you as there are also some forum members below your rank with more explanatory answers to what you may not understand.

I know this forum is full of Legends of Bitcoin. With Senior member I actually referred to members who are here for long time, not necessarily with higher rank, I believe in experience  Nevertheless, anyone can share their opinion if they have something to add here.

What using SegWit addresses does is make any resulting transaction smaller in terms of bytes, so the same fee rate in sats/vbyte works out as a smaller overall fee in sats. If you were to pay the same overall fee in sats as an identical transaction from a Legacy address, then your fee rate (sats/vbyte) would be higher, and therefore lead to a faster confirmation.

This is very confusing to everyone. So, segwit has nothing to do with fee(affecting indirectly though), it was generally implemented for reducing the transaction size? I used to think that it was for reducing fee.

[o_e_l_e_o]

So, segwit has nothing to do with fee(affecting indirectly though), it was generally implemented for reducing the transaction size? I used to think that it was for reducing fee.

It actually wasn't primarily implemented to reduce transaction size either, although both the transaction size decrease and fee decrease are what most users know it for.

It was initially implemented to fix the transaction malleability bug, which allows nodes to change the hashes of unconfirmed transactions. This was necessary for the Lightning Network to function. However, as a side effect of segregating the witness data, it counts the size of your transaction differently and effectively makes it smaller, meaning that we can fit more transactions in a block and you can save money on fees.

You can read more about it here: https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki
Or here (less technical): https://en.bitcoin.it/wiki/Segregated_Witness

[peempeem]

If I'm selling artwork, unless it's dirt cheap I am not going to let the buyer skimp on fees. I want a quick transaction.

If the art is worth like 5 bucks, then that is the use case for another coin, not bitcoin.

I think most of the market understands this already.

Skimping on fees is fine for moving between your own wallets but not for trading.

[khaled0111]

If I'm selling artwork, unless it's dirt cheap I am not going to let the buyer skimp on fees. I want a quick transaction.

If the art is worth like 5 bucks, then that is the use case for another coin, not bitcoin.

I think most of the market understands this already.

You can start accepting lightning payments. Using the lightning nework will significantly reduce transaction fees and your customers will have not to wait long time for confirmation as transactions are instant.

[o_e_l_e_o]

then that is the use case for another coin, not bitcoin.

Altcoins might be faster, but at the expense of less security. Have a look at https://github.com/lukechilds/howmanyconfs.com. Unfortunately the site itself has been down for a couple of months, but you can still see screenshots on the github. Even the fastest altcoins are several times slower than bitcoin to reach the same level of security, but the majority are closer to 100x slower or even more. There are also plenty of altcoins, including some major ones, which have been successfully 51% attacked.

Using altcoins has other problems too. I either have to plan all my purchases in advance so I can buy them as needed, or buy them in bulk and then slowly lose value on them since most of them just depreciate in relation to bitcoin. Much rather just use Lightning.

[RapTarX]

You can start accepting lightning payments. Using the lightning nework will significantly reduce transaction fees and your customers will have not to wait long time for confirmation as transactions are instant.

Although it's true that Lightning Network will reduce fee and solve the issue with scalibility, this is far away t be used. If there's no much settlement can be done in a channel, the fee will be more than normal transaction. I think there are a few to zero merchant is accepting payments through LN. LN can only be benefited for both the merchant and the customers, once there are a lot of merchant starts to accept payment through LN and LN channel get connected with all the available network, otherwise, as I said, fee will be much higher. You will not consider joining a channel just to pay one merchant.
Well, it's off topic here. I will soon create a topic on Lightning Network and it's possible output.