why does my transaction have so many inputs?

[leibnizster]

I have an old bitcoin wallet (Multibit) which I've ported over to Electrum using private key import.

I want to make a transfer of a small sum (around 1mBTC), but the fees I get are really high and that seems to be due to the large size of my payload (12KB with 86 inputs). The inputs seem to contain some of the transactions I already have in my history.

What I see is:

Inputs
0142...:36    myaddress    sum1
57 more like the above

Outputs
SCRIPT 20985...
myaddress   amount_id_have_left_after_transaction

A previous transaction I made 7 years ago just has 1 input and 2 outputs.
Why are all those transactions referenced as inputs? Has there been some sort of protocol change and this is necessary for some reason?

Thanks!

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[BitMaxz]

This is not the right time to transfer or send Bitcoins if you have lots of inputs from your wallet because the current network condition is congested so the wallet will ask for a high fee automatically.

If you don't want to pay a large fee you can manually set the fee on Electrum after you "pay", under the preview you can adjust the fee manually but the problem is if you pay lower than 120sat/byte your transaction might be stuck or it will take too long to confirm.

I suggest you wait for a few days until the unconfirmed transaction and mempool size drop you can monitor them from here https://jochen-hoenicke.de/queue/#0,24h

And then consolidate/merge your transaction for future transactions to get less fee and I suggest you switch to Segwit wallet.

You can follow this guide below on how to consolidate transaction
- https://bitcointalk.org/index.php?topic=2848987.0

[DannyHamilton]

A previous transaction I made 7 years ago just has 1 input and 2 outputs.

It must have been a small value transaction, and you must have sent an amount that was smaller than that input. Also, what sort of a fee did that transaction have?

Why are all those transactions referenced as inputs?

Without seeing the exact transactions being included and the exact transaction being created, it's difficult to say.  My best guess is that the transaction you are creating is for a larger value than any single available input in your wallet, and that each time it adds another input to cover the current cost, it increases the overall cost by making the transaction larger. It's stuck in a run-away loop trying to add value to the inputs side of the transaction by including more inputs, but the values of those inputs are so small that they don't even cover their own additional cost to send. This tends to happen when people acquire lots of extremely tiny value transactions from faucets or sig ad campaigns.

Has there been some sort of protocol change and this is necessary for some reason?

No. The protocol has always been like this. However, really early in Bitcoin's history it was possible to send transactions with NO fee at all, and since the blocks weren't ever full, the miners would just include it in their block for the sake of keeping the network running.

[leibnizster]

Thanks for the help.

So, I've discovered the coins tab and I was able to select a single input to use for my transaction. Is the default behaviour to select all possible inputs? There were lots of entries available that were larger than the sum I want to transfer, but the wallet decided to use them all for the transaction.

In my case, does it make sense to do that and manually select an input when I want to make a transfer? Since the fee/byte is so large right now. Is there any downside to doing that?

[ranochigo]

So, I've discovered the coins tab and I was able to select a single input to use for my transaction. Is the default behaviour to select all possible inputs? There were lots of entries available that were larger than the sum I want to transfer, but the wallet decided to use them all for the transaction.

Shouldn't be. The coin control algorithm was actually changed and there were configurations to tell the wallet to choose all or only as needed. Current client does not explicitly give the user the choice to select them. It would make sense to use Coin Control to send what you need. However, do keep in mind that you should consolidate them by spending them all when the transaction fees are lower. It's typically lower on Sundays and you should be able to get it confirmed for a reasonable fee.

If you don't, the caveat is that it won't be efficient to send a transaction during the times where the network gets more congested.

In my case, does it make sense to do that and manually select an input when I want to make a transfer? Since the fee/byte is so large right now. Is there any downside to doing that?

No downside. It'll be the best if you could select the inputs which are able to cover both your Bitcoins sent as well as the fees incurred.

[DannyHamilton]

you should consolidate them by spending them all when the transaction fees are lower. It's typically lower on Sundays and you should be able to get it confirmed for a reasonable fee.

I agree.  If it were me, and I wasn't planning on using any of the bitcoins in the next week or two, then I'd probably create a single transaction that spent EVERY output that had a value greater than 0.000003 BTC. Then I'd create 1 (or perhaps a few depending on total value) new output paying a transaction fee of 0.00000001 per byte (or perhaps per 2-bytes).  I'd set it up as a "Use Replace-By-Fee" (just in case I decide to bump the fee a bit after a few days), and Batch RBF. Then just wait for it to confirm. Could take a week or more. I'm not sure if Electrum re-broadcasts after a while to keep it fresh in the mempools, but if not then I'd re-broadcast once every few days.

Then when fees are higher (10's or 100's of satoshis per byte), you'll be able to send a lot cheaper.

[o_e_l_e_o]

Since the fee/byte is so large right now. Is there any downside to doing that?

Not only is there no downside, but I would suggest doing that for every transaction you make, so as to deliberately use the smallest number of inputs necessary to cover your transaction.

Then I'd create 1 (or perhaps a few depending on total value) new output paying a transaction fee of 0.00000001 per byte (or perhaps per 2-bytes).

Spending a fee of 1 sat per 2 vbytes, or 0.5 sats/vbyte, will not be relayed by the majority of nodes, since the DEFAULT_MIN_RELAY_TX_FEE is 1000 satoshi per vkB, or 1 sat/vbyte. You can see this in the code here: https://github.com/bitcoin/bitcoin/blob/16b784d953365bb2d7ae65acd2b20a79ef8ba7b6/src/validation.h#L56

[leibnizster]

you should consolidate them by spending them all when the transaction fees are lower. It's typically lower on Sundays and you should be able to get it confirmed for a reasonable fee.

I agree.  If it were me, and I wasn't planning on using any of the bitcoins in the next week or two, then I'd probably create a single transaction that spent EVERY output that had a value greater than 0.000003 BTC. Then I'd create 1 (or perhaps a few depending on total value) new output paying a transaction fee of 0.00000001 per byte (or perhaps per 2-bytes).  I'd set it up as a "Use Replace-By-Fee" (just in case I decide to bump the fee a bit after a few days), and Batch RBF. Then just wait for it to confirm. Could take a week or more. I'm not sure if Electrum re-broadcasts after a while to keep it fresh in the mempools, but if not then I'd re-broadcast once every few days.

Then when fees are higher (10's or 100's of satoshis per byte), you'll be able to send a lot cheaper.

Is this information reliable - https://bitcoinfees.earn.com ? If I understood correctly, that means that a 1 sat/byte transaction would get confirmed in maximum 11 hours (estimated by whoever manages the site). When you say re-broadcast every few days, how exactly do I do that? And why would I need more than 1 output depending of the total value?

Thanks!

[Abdussamad]

you can set a custom fee to spend those small inputs. it'll take a long time for the transaction to confirm but you'll have consolidated those small inputs:

https://bitcoinelectrum.com/how-to-manually-set-transaction-fees/

the answer to your original question is that you happen to have a lot of small unspent outputs perhaps from mining or faucets. you may not have realized at the time but those cost a pretty penny to spend.

[ranochigo]

Is this information reliable - https://bitcoinfees.earn.com ? If I understood correctly, that means that a 1 sat/byte transaction would get confirmed in maximum 11 hours (estimated by whoever manages the site). When you say re-broadcast every few days, how exactly do I do that? And why would I need more than 1 output depending of the total value?

No, it's inaccurate.

The network is very unpredictable and no fee estimation website or software can accurately predict the spike in the number of transactions or transactions with higher fees. I would think that transactions with 1 sat/byte fees would typically take up to days or weeks to confirm.

Rebroadcasting the transaction ensures that it never drops out of the memory pool and that the miners will always be able to see and potentially mine your transaction. You can just open your client, right-click your transaction, View Transaction and see if the rebroadcast transaction is available. It happens when the server that you're connected to has already dropped your transaction. If not, go to the View Transaction> Export (at the bottom left corner) and press Copy to clipboard.

Here are some of the sites that allows you to submit your own transaction:
https://en.bitcoin.it/wiki/Transaction_broadcasting

[o_e_l_e_o]

If I understood correctly, that means that a 1 sat/byte transaction would get confirmed in maximum 11 hours (estimated by whoever manages the site).

Yeah, that site is terrible I would suggest you do not use it.

There are 62 MB of transactions sitting unconfirmed in the mempool right now. If we got a steady 6 blocks an hour for the next 11 hours, and if not a single new transaction entered the mempool during these 11 hours, then yes, a 1 sat/vbyte transaction would confirm in 11 hours, but neither of things are ever going to happen. In reality, it has been over 2 weeks since 1 sat/vbyte transaction were being reliably confirmed, and it could well be that length of time again until they are.

There is no point trying to consolidate with a low fee at the moment - your transaction will sit unconfirmed for days or weeks, and it could potentially cause you problems if you don't enable RBF and end up with your funds tied up in an unconfirmed transaction. Just wait until fees are low again and then consolidate.

And why would I need more than 1 output depending of the total value?

If you want to spend more bitcoin than you have in a single input, then you will need to include multiple inputs in the transaction to cover the total value. And unless you want to send all the bitcoin in those inputs to the recipient, then you will need a second output to return the change back to yourself.

[leibnizster]

Thanks everyone. It's all clear to me now.

[Abdussamad]

rbf is on by default now. it doesn't hurt to broadcast a low fee transaction. you're just going to have to rebroadcast it periodically because the chances are high that it'll be ejected from nodes' mempools. it'll be marked as local in electrum history tab and you just right click on it , view transaction and click broadcast.

[DannyHamilton]

And why would I need more than 1 output depending of the total value?

That's just a matter of personal preference.

Anytime you want to spend bitcoins, the wallet software needs to choose one or more unspent outputs to spend.

If ALL your value is in a single unspent output, then when sending you'll never need to include more than 1 unspent output as an input, and your entire balance will be included in that transaction.  The good thing about that is that you'll never have more than 1 input in the transaction which can help keep the size of the transaction down.

Some of the bad things about that are:
Unless you are emptying your wallet out, you'll never have less than 2 outputs in any transaction (since you'll always need to send the change back to yourself).  If you split the wallet balanced up into a few smaller amounts, then you'd potentially have more opportunities to spend an entire input without needing any change back. It won't happen often, and it might not be worth the extra cost to need 2 inputs when you want to send more than the value of any single input, but it's something to be aware of.
 
If you have an exceptionally large amount of bitcoin, it can feel a bit overwhelming to know that your entire balance is being included in that 0.0002 BTC transaction.  You may know it will be sent back to you as change and know everything will be fine, but the thought that ALL of your bitcoin are being used to create that tiny transaction may still make you feel a bit feel queasy. By having multiple smaller amounts, you can include much less of your bitcoin in the transaction.

If your transaction isn't confirmed right away (sudden spike in transaction fees?) then many wallets will block you from sending ANY of the "change" from the transaction until the initial transaction first confirms.  Also some merchants might be unwilling to accept a 0-confirmation transaction when the input isn't confirmed yet either.  This could force you to wait longer than you'd hoped to complete a subsequent transaction. By having multiple smaller amounts, you can use some of them in one transaction, and still have others that are confirmed and ready to go for additional transactions.

For that matter, Electrum will let you have multiple wallet files.  You can send most of your bitcoin to an address (or some addresses) from one wallet file that you rarely access, and send just a small amount of "weekly spending" bitcoin to an address (or some addresses) from another "main" file that you typically open.  Create GREAT backups of the "archive" wallet, and then remove the wallet file from your computer entirely.  Now if your computer and/or password is ever compromised they'll only have access to your "weekly spending" and not your vault.

[o_e_l_e_o]

If you have an exceptionally large amount of bitcoin, it can feel a bit overwhelming to know that your entire balance is being included in that 0.0002 BTC transaction.

It's also terrible for your privacy to have all your bitcoin in a single output for a small transaction like this. Do you really want the guy selling you coffee or the guy you are trading $50 worth of bitcoin with to see an input of 10 BTC and know that you are holding that much? You don't want to reveal the entire balance of your bank account every time you buy groceries, and you don't want to do the same thing with bitcoin.

As you say, it's better to have different wallets for different purposes. Some form of cold wallet (be that hardware, paper, airgapped) to hold the majority of your funds very securely, and then a hot wallet such as on your computer or phone with a smaller amount of bitcoin for regular spending. Even better to try to keep the two unlinked in terms of blockchain analysis by using mixers or coinjoins so you also have plausible deniability in the case of a $5 wrench attack.

[leibnizster]

If you have an exceptionally large amount of bitcoin, it can feel a bit overwhelming to know that your entire balance is being included in that 0.0002 BTC transaction.

It's also terrible for your privacy to have all your bitcoin in a single output for a small transaction like this. Do you really want the guy selling you coffee or the guy you are trading $50 worth of bitcoin with to see an input of 10 BTC and know that you are holding that much? You don't want to reveal the entire balance of your bank account every time you buy groceries, and you don't want to do the same thing with bitcoin.

As you say, it's better to have different wallets for different purposes. Some form of cold wallet (be that hardware, paper, airgapped) to hold the majority of your funds very securely, and then a hot wallet such as on your computer or phone with a smaller amount of bitcoin for regular spending. Even better to try to keep the two unlinked in terms of blockchain analysis by using mixers or coinjoins so you also have plausible deniability in the case of a $5 wrench attack.

Regarding you "bank account" argument, many inputs/outputs wouldn't help with hiding your overall worth, right? Even if you do that, anyone curious enough will be easily able to find out the total amount of BTC you have in your wallet, as it's all public. The only way to prevent this would be to have separated wallets, right? So I get the argument of not wanting to send 100BTC in each transaction, but that won't for the privacy of your wallet net worth. Unless I misunderstood something.

[o_e_l_e_o]

Even if you do that, anyone curious enough will be easily able to find out the total amount of BTC you have in your wallet, as it's all public.

Only if they know all your addresses, which is only possible if you have either linked all your addresses together by using them together in the same transaction, or if you have told someone all your addresses. There is no way just by looking at an address to find out which other addresses are part of the same wallet.

If I have 10 BTC on Address A, and 0.1 BTC on Address B, and I send you 0.01 BTC from Address B, then all you will know is that I had 0.1 BTC on Address B. You will only be able to discover that I also own 10 BTC on another address if I also make a transaction (either previously or in the future) which uses coins from both Address A and Address B together.

If you take care not to link your address together like this, and otherwise don't tell people which addresses you own or reveal your wallet details/public keys/etc., then your privacy is maintained.

[ranochigo]

Regarding you "bank account" argument, many inputs/outputs wouldn't help with hiding your overall worth, right? Even if you do that, anyone curious enough will be easily able to find out the total amount of BTC you have in your wallet, as it's all public. The only way to prevent this would be to have separated wallets, right? So I get the argument of not wanting to send 100BTC in each transaction, but that won't for the privacy of your wallet net worth. Unless I misunderstood something.

Agree. It'd be challenging to link the various addresses together to a single wallet if they were kept separately without any linked transactions or outputs being spent in the same transaction. The argument would mainly be geared towards keeping funds on separate wallets/addresses that are never linked, which would also mean that you're not spending your entire Bitcoins in your transactions. If you really want privacy, you'll be looking to use CoinJoin/Mixer after the consolidation to separate it into different addresses and/or wallets.

[leibnizster]

Even if you do that, anyone curious enough will be easily able to find out the total amount of BTC you have in your wallet, as it's all public.

Only if they know all your addresses, which is only possible if you have either linked all your addresses together by using them together in the same transaction, or if you have told someone all your addresses. There is no way just by looking at an address to find out which other addresses are part of the same wallet.

If I have 10 BTC on Address A, and 0.1 BTC on Address B, and I send you 0.01 BTC from Address B, then all you will know is that I had 0.1 BTC on Address B. You will only be able to discover that I also own 10 BTC on another address if I also make a transaction (either previously or in the future) which uses coins from both Address A and Address B together.

If you take care not to link your address together like this, and otherwise don't tell people which addresses you own or reveal your wallet details/public keys/etc., then your privacy is maintained.

OK, now it all makes sense. Previously (7 years ago), I've only used a single wallet address for everything - I thought you'd need a different wallet to get a new address. Thanks for the clarification.

[o_e_l_e_o]

Previously (7 years ago), I've only used a single wallet address for everything - I thought you'd need a different wallet to get a new address. Thanks for the clarification.

Any half decent modern wallet will be able to provide you with essentially as many addresses as you want. I can't necessarily say the same for all wallets from back in 2014. Do you know the name of the wallet you were using back then? Are you still using it?

Most wallets these days which are not Bitcoin Core are what is known as hierarchical deterministic wallets. They provide you with a seed phrase, also known as a recovery phrase or mnemonic phrase, which is a list of usually 12 or 24 words. These words back up your entire wallet, and addresses are generated deterministically from these words. By that we mean that the same words will always reproduce the same addresses in the same order. So if you write down your 12 or 24 words, then that effectively backs up every address in your wallet, including ones you haven't generated yet. Theoretically, one set of words could generate trillions of trillions of trillions of addresses, although obviously no one would ever need that many.

Bitcoin Core does not use seed phrases to generate addresses, and so if you are using Bitcoin Core instead of backing up your seed phrase you need to back up your wallet.dat file.