How Are Crypto Transactions Confirmed?

Knowing how your transaction is confirmed is the basis on which you can build your understanding of cryptocurrency. This is a technically difficult process, but you can grasp it without special terms — today, we will explain to you how it works. Let’s take Bitcoin as an example.

How do Bitcoin transactions get confirmed?

Transactions for which users set higher fees are prioritized by miners — they are trying to make maximum profit from their work. When a node mines a block with your transaction and adds it to the blockchain, it means your transaction has been confirmed.

Why do I have to wait for confirmations?

When your transaction is added to a block, this means it has got a confirmation. When another 10 minutes pass and one more block is mined, that means your transaction now has 2 confirmations. And so on — within 24 hours, a transaction gets around 140 confirmations.

If you pay for some goods or services or deposit money on an exchange, you may be asked to wait for a few confirmations. This can be fixed (2–3 confirmations) or flexible: the more money you send in a transaction, the more confirmations it needs. For transactions worth over $10,000, 6–10 confirmations may be required, and for those worth $1 million and more, it can be about 60.

Why is that needed, given that transactions are irreversible and once they make it into a blockchain, they will stay there forever? The thing is that shops and exchanges want to protect from potential attacks on the Bitcoin network. Attacking BTC is very expensive and there haven’t been cases lately, but this is highly relevant to other coins — for instance, Ethereum Classic (ETC) has experienced two 51% attacks in the last few years.

When an attack happens, malicious actors take control over at least 51% of the network’s nodes and can put any data that they want in the blockchain. They may even cancel your transaction. However, this is possible only for the latest blocks — the older a block, the more difficult it is to reach it and alter it. 2–3 confirmations and especially 10 is a reliable indicator that nothing will happen to a transaction and it’s now forever in the blockchain.

How to set a good fee?

Setting this is possible in Atomic and Guarda wallets. Choose the currency, click “Send”, and then “Set fee”. You will see that fees are measured in sat/B, or satoshis per byte (1 Satoshi is one hundred millionth of Bitcoin — 0.00000001 BTC). By default, the fee will be set for the fastest confirmation time (about 100 sat/B).

Here, you can see how fast the transactions with different fees are confirmed. If you are not in a hurry, set a lower fee to save money — but make sure you don’t make it too low. With fees below 5–10 sat/B, a transaction may get stuck for hours and even days: miners will be disincentivized to take it from the mempool. To check the overall state of the latter, see Mempool.Space.

How long do I have to wait for a confirmation?

Ethereum was one of the first platforms to drastically improve this indicator, and its block time is 15 seconds. Even this is considered quite long today: such coins as Solana and Nano process transactions in less than a second, and the fees are extremely low or even absent.

Can ChangeNOW speed up the confirmation time for my transaction?

My transactions get stuck often. What can I do?

How do I check if my transaction was confirmed?

I used ChangeNOW to swap my coins, and my transaction got stuck. What can I do?

Tips to spend less on network fees

  • If several hours won’t make much difference to you, lower the fee. Don’t make it too low, though — otherwise your transaction may get stuck.
  • If you are planning a few similar transactions, think of organizing them into one single payment. Fees don’t depend on the transaction size, so by putting a few into one, you’re saving a considerable amount of money.

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