# Block time and confirmation time

I have been reading in different papers and comments these two concepts and I would like to know the difference between them(if there is, sometimes it is a bit confusing).

I understand that the block time is the period for collecting transactions, the time that to mine a block takes, and the confirmation time is the time to put a transaction in a block. I am not sure if it is correct. If it is true, is it possible to get the confirmation time of a transaction? What do these times depend on?

I know that there are more open questions here talking about this, but I do not get the concept very well and I cannot comment on the threads, so I would appreciate the help.

## 1 Answer

Block time is the expected interval between two blocks. For ethereum, this is around 15 seconds. For Bitcoin, it is 10 minutes.

The number of confirmations is simply the number of blocks that have been mined after the block that contains your transaction, and include that block in their chain history. There is no concept such as "confirmation time", since this will vary by the number of blocks you consider to be irreversible. Most exchange and merchants will use anything from 10-50 confirmations for ethereum, or 2-6 for Bitcoin.

Transaction gathering, on the other hand, is a continuous process. Even while mining block `N`, miners are collecting transactions for block `N+1` as new transactions are submitted to the tx pool.

• I still have a doubt. When we talk about "confirm", we are talking about confirming transactions (not blocks(?)), and I understand that it is when the miner adds a transaction in the block, but in your response, you talk about confirming blocks (one confirmation is one block mined). Does that mean that there are two types of confirmations (for tx and blocks)? Aug 12, 2018 at 8:19
• When we talk about `confirmations` we mean the number of blocks that were created after the block we are talking about. This is the formula: `confirmations`=`last_mined_block_number`-`block_number_you_are_asking_confirmations_of` Aug 12, 2018 at 16:37
• Number of mined transactions has nothing to do with `confirmations` you can have blocks with 0 transactions in all of then, and you are going to have confirmations anyway. Aug 12, 2018 at 16:38