Monero: 10 confirmations requirement
This article goes into detail about the necessity for having 10 confirmations in Monero transactions and what this means for you.
Why do we need 10 confirmations?
When you send a Monero payment, it will be announced to the Monero network instantly. However, it is not enough to rely on that announcement, because a sender could make multiple such announcements in an attempt to 'double spend' their funds.
So Monero, of course, has to secure against double-spends as well as orphaned blocks, user error, bad actors and other such exploits. This is why the announcement of the transaction needs to be 'mined' into a block by the network of Monero nodes.
Just like practically every other cryptocurrency, two things happen when you send Monero:
- The transaction gets broadcast and placed in a transaction pool (Your wallet will see this almost straight away).
- Your Monero is locked until it is mined in a block and then a certain number of subsequent blocks have been mined afterwards to be 'confirmed'. In Monero's case, wallets keep the funds locked for 10 blocks.
What does waiting for 10 confirmations mean for me?
Reading above you would have seen that your Monero may be locked however please do not worry and allow us to explain:
The best way to think about this is to see the similarities to Bitcoin confirmations and change addresses. When you initially receive outputs, they are locked which just means they are not able to be spent until the transaction has 10 confirmations.
Being similar to Bitcoin’s change addresses, Monero works in a way that has change outputs; which are unique one-time public keys and therefore you may encounter a locked amount of XMR even when sending to another wallet.
Let's have an example here to illustrate what we mean: Say you have a balance of 10 XMR.
- One spendable output of full 10 XMR:
In this example when you send 2 XMR to someone, this whole 10 XMR output gets used and the change comes back to you in a new output. Let’s say your fees were 0.01. Your transaction, therefore, sends one output with 10 XMR, and has 2 outputs, one for 2 XMR (the recipient) and one for 7.99 XMR (your change). Because the transaction needs to be confirmed, your change (7.99 XMR), will be locked until it has 10 confirmations.
- Two or more spendable outputs of 3 XMR and 7 XMR:
If the original balance was spread over 2 spendable outputs and you just want to send 2 XMR, only one of those outputs would be used, say the 3 XMR output. That means only your change left over from just the 3 XMR output would be locked until 10 confirmations. The other output of 7 XMR is untouched and would not be locked and would be free to spend straight away. Only what is spent needs to wait for 10 confirmations.
In short: any funds that have been spent for any reason will be locked until it has achieved 10 confirmations. For Monero transactions, reaching 10 confirmations on average should take 20 minutes.