Bitcoin Confirmations – All you need to know about block confirmations

Whether you send Bitcoin or receive Bitcoin; the status of your transaction will initially remain “unconfirmed”. Once the transaction is verified and successfully included in the blockchain the status will then change to “confirmed“. In Bitcoin; for the “unconfirmed transaction” to become “confirmed” that is to get 1 confirmation it will take about 10 minutes. After it gets confirmed; is the transaction successfully complete or we need to wait for more confirmations?

There are occurrence for example let’s say you send BTC to your exchange account. Even though the status of your transaction is confirmed your deposit amount will not yet be credited. Why is that? That’s because the exchange has a certain block confirmation requirements before they can show you your transaction amount. If you are new to Bitcoin then you might be wondering the difference between “confirmed” and “unconfirmed” transactions and why some services require more confirmations than the others.

Here in this post we’ll explain everything that you need to know about Bitcoin confirmations. What does confirmations required mean? What are the ways to check Bitcoin transaction confirmations? How many Bitcoin confirmations are required for the transaction to be successful? How many confirmations are required before the transaction becomes spendable? Why 6 confirmations are considered secure and how long does it take for a transaction to get 1 confirmation?

What are Bitcoin confirmations?

Bitcoin is a decentralized crypto currency that uses Blockchain technology. Blockchain is a distributed public ledger. It is a continuously growing list of records that contains all Bitcoin transaction data from the beginning to now. The transaction information that is being recorded into blockchain can only be added and cannot be removed. Once it is included, it remains included forever. On average; every 10 minutes a new block is created and gets added to the Bitcoin blockchain. All these new blocks are created through the process called mining and every single block contains transaction data that are verified by the miners.

Bitcoin transaction that is confirmed means the transaction that is broadcasted to the network is verified and included in a block. Each Bitcoin confirmations represents the total number of blocks that are generated since the block that has your transaction details. For better understanding let’s see how Bitcoin block confirmations work.

How Bitcoin block confirmations work?

Let’s say you send some Bitcoin to your Friend. Now before this transaction gets included in a block it goes into a pool of unconfirmed Bitcoin transactions called Bitcoin Mempool. Now the miners will pick your transaction from this mempool and place it in a block along with other unconfirmed transactions. Then miners start solving a complicated mathematical puzzle. Once they produce proof of work solution for the block which contains your transaction the block will get confirmed by the network and gets added to the end of the blockchain.

The moment the block gets added to the blockchain; all the transactions that are in the block will have 1 confirmation. This process on average will take around 10 minutes. After the block gets included in the blockchain it continuously gets buried under every new block that is created on the network. Each block will have an interval of 10 minutes and every new block created after your block will reconfirm your transaction. That is with each following block that is found; the number of confirmations for your transaction increases.

Since the block time of Bitcoin is 10 minutes to get 3 confirmations it will take about 30 minutes and to get 6 confirmations it will take 60 minutes. Okay, now how to check the confirmation status for your transaction.

How to check transaction confirmations?

Whether you sent / receive money using Bitcoin core wallet, electrum wallet, or any light wallet; the client gives you an option to view your transaction details. It displays the total amount that is transacted, its size, transaction ID and the transaction status. That is the total number of block confirmations that your transaction has received so far.

In addition to this you can also use Block explorer to check your transaction confirmations. All you need to do is enter your wallet address or the transaction ID which looks something like this:

aa8ab4868b0f101cf304add8017bb6aeaee97dfc985571740140edf9780d8d0d

The service will display the number of confirmations that your transaction has received.

Okay, so how long does it takes to get 1 confirmation?

Bitcoin confirmation times

The average block time of Bitcoin is 10 minutes. But not all transactions are confirmed in 10 minutes. It could take hours or it could even take a day to get 1 confirmation and it depends on few factors. In Bitcoin all transactions are processed only through miners and due to this transactions are subject to delays. Two reasons that causes delay in transaction are network congestion and low transaction fees.

Miners prioritize transactions that pays higher fees. If your transaction is taking a long time to get 1 confirmation then you might have not included a reasonable transaction fees. If your transaction includes large enough miner fee then there is more than 60% chance that it will get confirmed within the next 10 minutes.

To learn more transaction fees and time we suggest you read this topic on Mempool.

Okay, now the next question is how many confirmations are needed?

Number of confirmations required

Actually you can spend the output of transaction that has 0 confirmations. Zero confirmation is nothing but a transaction that is not yet part of the blockchain. The transaction that has 1 confirmation means it is accepted by the blockchain. If you are receiving a payment from a trusted party you can accept their transaction even if it has 0 confirmations (unconfirmed). If you are a merchant accepting Bitcoin then for small payments 1 confirmation is enough. But remember that a transaction that has 0 and 1 confirmations can be reversed.

Zero confirmation transactions are more prone to Race attack and Finney attack. Whereas 1 confirmation transactions are vulnerable to 51% attack. With 0 and 1 confirmation double spending (double-spend attack) is possible. Double spending is a practice in which an user attempts to spend same money more than ones. This is why majority of exchanges require 2 to 3 confirmations. But the industry standard is 6 confirmations which takes approximately 1 hour and it is considered safe and secure. So why 6 confirmations?

Why 6 confirmations?

Bitcoin transactions are recorded in a distributed ledger. There is no central authority to consult whether if a transaction is successful or not. Since the system is decentralized the community considers transaction confirmation numbers as a validity. There is nothing special about 6 confirmations. This number is chosen assuming that it would cost an attacker more in order to double spend. With 6 confirmations it becomes practically impossible for an attacker to re-org and reverse a transaction, create an alternate chain faster than the original chain.

In Bitcoin the longest chain wins. So not just 6 confirmations; the more on-chain confirmations your transaction has the harder it is to rewrite.

If you need more logical explanation on why 6 confirmations is required then go through this topic.

Bitcoin requires 6 confirmations and each block confirmation take about 10 minutes. But what about Ethereum, Litecoin, Monero and other services that accepts Bitcoin?

How many confirmations does it need? Coinbase, Litecoin, Ethereum, Dash, Monero

The block confirmation time and number varies from coin to coin. Not only varies for coins but each and every service that accepts cryptocurrency will have a certain requirement on block confirmations. Following are the confirmation requirements for the popular cryptocurrencies and exchanges.

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