What are Bitcoin Blocks and Bitcoin Confirmations ?

Last updated on March 18th, 2015 at 10:43 am

Let’s say I send you 1 Bitcoin. After a few minutes you see that this transaction has received one “confirmation”. What does this actually mean?

The block chain is built out of “blocks”. Each new block is a set of new unique Bitcoin transactions that were recently made. So when I broadcasted to the network that I want to send you 1 Bitcoin the transaction went into an unconfirmed transactions pool.

Miners entered the unconfirmed transactions pool, took this transaction and others like it, verified they were valid (meaning I actually have the 1 Bitcoin to spend), and grouped them into a block. The new block is set at the top of the blockchain and is considered confirmed. Now miners can move on to build the next block on top of that one.

Each time a new block is built it means that the older blocks got confirmed again (since they are checked also in the process). The more confirmations you get, the harder it will be for someone to manipulate the system and remove the block containing this transaction from the wall (or blockchain) since it’s buried under the other blocks that were confirmed.

It is recommended to wait for at least 6 confirmations in order to be 99.9% sure that your transaction won’t get canceled – this takes roughly 1 hour to achieve. If you’re dealing with smaller amounts of money you’re probably OK with waiting for just 1 confirmation.

Reversing a transaction takes planning, time and effort and a lot of computing power. Most people probably won’t go through all of that trouble for a small amount of money.

Ofir Beigel

Owner at 99 Coins ltd.
Blogger and owner of 99Bitcoins. I've been dealing with Bitcoin since the beginning of 2013 and it taught me a lesson in finance that I couldn't get anywhere else on the planet. I'm not a techie, I don't understand "Hashes" and "Protocols", I designed this website with people like myself in mind. My expertise is online marketing and I've dedicated a large portion of 99Bitcoins to Bitcoin marketing.

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30 Comments on "What are Bitcoin Blocks and Bitcoin Confirmations ?"

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Samurai
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Samurai

Hi i have one question. I use blockchain miner pro and i need comfirmations to transfepere my BTC from program wallet to my real wallet (i mean to paypal) so how i can get confirmations ?

Steven Hay
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Steven Hay

Hey Samurai,

OK to clarify, you’ve mined some amount of bitcoins but you’re struggling to withdraw them? First check that the amount you’ve mined is above the minimum allowed withdrawal from the app. Secondly, once you’ve successfully withdrawn the bitcoins, you’ll need to swap them for fiat currency (USD, EUR, etc.), which you’ll withdraw to your bank account. You can then use the fiat to fund your PayPal account.

Samurai
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Samurai

thanks a lot man i try to do this ;)

Alyxs
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Alyxs

how many good share i have to make for confirmation block

Steven Hay
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Steven Hay

Hi Alyxs,

I’m sorry but I don’t understand your question. Please ask it in a different way…

What do you mean by good share?

ExMachina
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ExMachina

I have some questions. How exactly do all miners share the same ledger? I mean, if miner goes offline for a bit, he would need to refresh his ledger, how would he do that and how would he confirm integrity of the new blocks? Would he just update the ledger from several different nodes? What if those nodes contradict with each other? What if more than a half of those nodes are compromised? Is blockchain vulnerable to sybil attack in general?

Steven Hay
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Steven Hay
Hey ExMachina, OK, these are some pretty deep questions… The purpose of the blockchain is to maintain a ledger which is synchronised and correct for all participants, yet not controlled by any single entity. How this is achieved is explained in Satoshi’s white paper and our Beginner’s Course and blockchain article: https://99bitcoins.com/what-is-blockchain/ If a miner goes offline, there’s no way he can refresh his version of the blockchain without going back online and reconnecting. When the miner returns, his software automatically verifies the integrity of the new blocks he receives. The new blocks must agree with and follow from his… Read more »
john borrow
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john borrow

I am mining a small amount of bitcoin on the Genisis platform. I don’t want to sell, but if I did, how would I do this? I can’t see any sell options anywhere on the site..

John Borrow

Zsofia Elek
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Zsofia Elek

Hi John, the mined Bitcoins are in your wallet, you can send the coins to an exchange where you can sell them. Here you can find couple of exchanges with reviews where you can buy and sell Bitcoins: https://99bitcoins.com/best-bitcoin-exchanges-comparison-review/

rawlings frakenstein
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rawlings frakenstein

How to make profit through buying and selling of bitcoins

Zsofia Elek
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Zsofia Elek

Hi Rawlings, here is an article which summarizes the important points about investing in Bitcoin: https://99bitcoins.com/should-i-invest-in-bitcoin-heres-what-you-need-to-know/

Mulaa
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Mulaa

I don’t know how I stumbled on this blog and after a few videos I can say it is awesome

JAMES JOHNSON
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JAMES JOHNSON

my transaction pending with bitcoin for two days

Zsofia Elek
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Zsofia Elek

Hi James, this article explains why do you have to wait sometimes for the Bitcoin transactions to go through. I can be useful for you: https://99bitcoins.com/why-bitcoin-transaction-pending-bitcoin-fees/

BRIGHT OMOAREBU
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BRIGHT OMOAREBU

Thanks a bunch, Ofir. I am really learning much and uping my knowledge in Bitcoin.

muhamma dasuki bin khaaja kamarudin
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muhamma dasuki bin khaaja kamarudin

Tq So Much.. This video..

vittorio
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vittorio

I am really enjoying this videos.
thanks

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