Bitcoin Forum

https://blockchain.info/tx/0665ff0d558c50dc0a6b79c9442b683d2a64e1517228e6640eea0718b1bc0ee1

In the above tax id i sent 0.0022 BTC to the address: 1NQnBRwQj7zh2e51MSZQoyhvphyAYrMdVb from 14D7ZgS8D5Z86QHEbrc5xQjg1Rk1xGkTaV
but then by itself 0.00723515 BTC went to 1Hm1wLW9HWomyFXw8J7fHYgvfCXc8Xe617 and now i only have 0.0004 BTC in my original address which I sent from: 14D7ZgS8D5Z86QHEbrc5xQjg1Rk1xGkTaV

So i'm wondering did I actually just lose those coins or not because my bitcoin QT still says that I have 0.00763515 BTC Left in my wallet.

http://snag.gy/y3xu3.jpg

Please do not use blockchain.info (or other blockchain explorers) to try to understand your wallet.  They aren't operating your wallet, and they don't know what your wallet is doing.  They try to guess, but they frequently guess incorrectly.  Using a blockchain explorer run by a third party company to try to track the balance in your wallet is only going to lead to confusion on your part.


No, you did not.  Bitcoins aren't sent "from" addresses.  Addresses are used for receiving bitcoins, not sending them.  You sent 0.0022 BTC from your wallet.  A wallet tracks and controls multiple addresses. Depending on the wallet that you are using, it may not even tell you about all the addresses that it uses for internal processes.


This is referred to as "change".

If you go to a store with a $20 bill and pay for something that costs $10, you can't rip the bill in half to pay for it.  Instead you give the store the entire $20 bill, and they give you back a $10 bill as change which you put back into your wallet.

When you spend bitcoins, you spend previously received unspent outputs.  If an unspent output is going to be spent, it must be spent in it's entirety.  You can't "rip it in half".  Therefore, your wallet spends the entire output, and then sends a new output with your change back into your wallet at a new address.

In this particular transaction you spent a 0.00944119 BTC output that you received approximately 3 hours earlier.  You paid a 0.00000604 BTC, and received 0.00723515 BTC back in "change".


Satoshi explained in his whitepaper that you should use a new address for EVERY TRANSACTION that you receive.  You should think of an address as an invoice number or a payment number, and not as an account number. If you were using bitcoin the way Satoshi recommended (and the way that gives you more security and more financial privacy), then you wouldn't have anything left at the 14D7ZgS8D5Z86QHEbrc5xQjg1Rk1xGkTaV address at all, since it only would have had one output to start with and that output would be spent. Instead your entire balance would be held in other addresses in your wallet.

Since you have chosen to reuse the 14D7ZgS8D5Z86QHEbrc5xQjg1Rk1xGkTaV for multiple transactions, you still have associated with that address a 0.0004 BTC unspent transaction output that was received approximately 1 minute prior to the 0.00944119 BTC.


Your wallet is telling you that you still have bitcoins in your wallet.  Why don't you believe it?

It's a "change address", you'll find that address in your wallet, it is yours, you can even set a fixed address for change.

When you send bitcoins you may not be able to send the exact amount, so the change is send back to you, let's say you have an input of 1 bitcoin and you want to send 0.5 bitcoin, when you send the 0.5 btc you are sending your entire input of 1 btc but 0.5 is sent back to you.

Thx this really helped me alot

Seriously, all of these "my BTC was sent an address I don't know" posts are ridiculous. It's like at least once a week about change addresses.

Whats so ridiculous about those questions? Its a hard to grasp concept that bitcoin comes in lumps and is not just a balance where one can deduct a certain any amount. The questions only shows that most wallets do a very good job in hiding the details of the implementation from the user and that blockchain explorers are an unreliable tool when trying to assess a wallet.

It's ridiculous that it's constantly happening. If people constantly have to ask you have a serious design flaw, but I don't expect the fucking morons around here to understand that.

Well, its not like you are going to get blockchain explorers removed just because they are badly designed. They serve a purpose after all and I wouldnt want to miss them. I think your expectations towards them (the blockchain explorers not the users) are a bit high.

I have no idea if you're complaining about the people asking the questions, or that change address implementation is flawed in some way, or if you're stating that the blockchain explorers are flawed.  Who exactly are the morons to whom you're referring?

DannyHamilton's explanation is very good.  You should not be using a blockchain explorer to track the operation of your wallet.  If you are going to look at the blockchain explorer, you really should have some idea of the workings of the protocol to know that transactions are composed of inputs and outputs.